Light emitting device

ABSTRACT

To minimize the variability in the emitted light color and improve the unevenness of color tone, a light emitting device comprises a light emitting element and a fluorescent substance that is excited by the light emitting element, wherein the light emitting element has an emission spectrum in a region from ultraviolet to visible light of short wavelengths, and the fluorescent substance has an emission spectrum that includes two or more emission peaks with at least two peaks of the two or more peaks being in the relation of complementary colors of each other.

TECHNICAL FIELD

[0001] The present invention relates to a light emitting device thatuses a light emitting element and a fluorescent substance and can beused for such applications as illumination, display, indicator and otherlight sources, and particularly to a white light emitting device thatuses a fluorescent substance that is excited by the light emitted by asemiconductor light emitting element and emits light having a spectrumin the visible region.

BACKGROUND ART

[0002] Various semiconductor light emitting elements have been developedsuch as light emitting diode and laser diode. These semiconductor lightemitting elements are replacing part of electric bulbs and cold cathoderay tubes as light sources for display, back light and indicator, bytaking advantage of such features as the capability to run on lowvoltage, small size, light weight, small thickness, long life, highreliability and low power consumption.

[0003] In recent years, such light emitting devices have been developedas nitride semiconductor is used as the light emitting element that canefficiently emit light in a region raging from ultraviolet to visiblelight of short wavelengths. Such LEDs capable of emitting blue or greenlight with 10 candela or higher luminous intensity have beencommercialized by using light emitting elements having quantum wellstructure with activation (light emission) layer made of nitridesemiconductor (for example, mixed crystal of InGaN).

[0004] It has also been made possible to carry out color mixingincluding white color by combining the light emitted by such an LED chip(light emitting element) and the light emitted by a fluorescentsubstance that is excited by the light of the LED chip thereby toproduce fluorescence.

[0005] Such light emitting diodes are disclosed, for example, inJapanese Non-examined Patent Publication No. 152609/1993, JapaneseNon-examined Patent Publication No. 153645/1997 and JapaneseNon-examined Patent Publication No. 10-242513/1998.

[0006] Specifically, the light emitting element is caused to emitultraviolet rays or blue light of relatively short wavelengths in thevisible region, and the fluorescent substance is excited by the light ofthis light emitting element so as to emit visible light of wavelengthslonger than the light emitted by the light emitting element. Theconstitution that employs color mixing of the light emitted by the lightemitting element (visible light) and the light emitted by thefluorescent substance has an advantage that the structure can besimplified and the output power can be increased, although color driftis likely to occur. When a light emitting element that emits ultravioletrays is used, on the other hand, such a constitution is employed asfluorescent substances capable of emitting light of red, green and bluecolors so as to produce white light are used, so that the color can beadjusted relatively easily since only the light emitted by thefluorescent substances is used. When a light emitting element that emitsultraviolet ray is used, in particular, mass productivity can beimproved since deviation of wavelength of the light emitted by thesemiconductor light emitting element can be accommodated somewhat andthe chromaticity can be determined only by the color of light emitted bythe fluorescent substance.

[0007] However, in the light emitting device of the prior art where twoor more kinds of fluorescent substance are used and a desired color isproduced by color mixing of the light emitted by the fluorescentsubstances, intensity ratio of light emitted by two fluorescentsubstances changes due to difference in the excitation spectrum betweenthe two fluorescent substances, when emission wavelength of the lightemitting element used in excitation changes.

[0008] As a result, in the light emitting device of the prior art wheretwo or more kinds of fluorescent substance are used, it has beendifficult to satisfactorily suppress the variation of chromaticity ofthe light emitting device since variability in the emission wavelengthof light emitting element affects the chromaticity of the light emittingdevice.

[0009] For the semiconductor light emitting element to be used as lightsource including illumination by making use of the advantage thereof,the light emitting device of the prior art is not satisfactory and it isrequired to increase the luminance and improve the mass productivity.

[0010] There has not been known any fluorescent substance that can beexcited by near ultraviolet rays or visible light of short wavelengthsso as to emit red light with sufficient luminance.

[0011] Therefore, there is such a case as the proportion of mixing thered light emitting fluorescent substance must be increased, whichresults in a decrease in the relative luminance. When the fluorescentsubstance is excited by near ultraviolet rays, variability in thewavelength of light emitted by the light emitting element may lead to adecrease in the luminance of red light emitted by the fluorescentsubstance due to the shift in the wavelength of light that excites thefluorescent substance, thus resulting in a change in chromaticity oflight emitted by the light emitting device.

[0012] Also in case the fluorescent substance is excited by afluorescent substance emitted by the light emitting element, it isdesired that a required color can be achieved by controlling thecomposition of the fluorescent substance in order to improve the massproductivity.

DISCLOSURE OF THE INVENTION

[0013] The present invention has been made to solve the problemsdescribed above. A first light emitting device according to the presentinvention comprises a light emitting element and a fluorescent substancethat is excited by the light emitting element, wherein the lightemitting element has an emission spectrum in a region from ultravioletto visible light of short wavelengths, and the fluorescent substance hasan emission spectrum that includes two or more emission peaks with atleast two peaks of the two or more peaks being in the relation ofcomplementary colors of each other.

[0014] As used herein, the expression that “two peaks are in therelation of complementary colors of each other” means that when a lightof one peak and a light of the other peak mixed, white light whichinclude greenish white, bluish white, purplish white, reddish white andyellowish can be obtained. For example, blue light and yellow light,blue green light and red light are in the relation of complementarycolors of each other. In the present invention, two peaks in therelation of complementary colors preferably are set so that one peak isset in the range of 380 nm-485 nm and the other peak is set in the rangeof 575 nm-630 nm.

[0015] In the chromaticity diagram, colors on a line perpendicular toPlanckian locus have same color temperature, if the colors are differentin the chromaticness. Therefore, in the direction of perpendicular toPlanckian locus, preferable white region cannot be defined by using thecolor temperature. However, two peaks in the relation of complementarycolors preferably are set so that the mixed light of one peak light andthe other peak light is positioned on Planckian locus or near toPlanckian locus to obtain the high emitting efficiency, since the lightpositioned on Planckian locus can be emitted with highest brightness.

[0016] The expression to have “an emission spectrum in a region fromultraviolet to visible light of short wavelengths” means that anemission spectrum in a region from 340 nm to 440 nm can be observed.

[0017] The first light emitting device according to the presentinvention having such a constitution as described above can minimize thevariability in the emitted light color and improve the unevenness ofcolor tone, since the emission spectrum of the fluorescent substancehardly changes even when the emission spectrum of the fluorescentsubstance changes due to variability in the manufacturing process.

[0018] The first light emitting device of the present inventionpreferably has main emission wavelength of the light emitting elementlonger than 360 nm in the near ultraviolet region, which makes theconstitution simpler and mass production of the light emitting deviceeasier.

[0019] In the first light emitting device according to the presentinvention, it is preferable that, of the two emission peaks of thefluorescent substance that are in the relation of complementary colorsof each other, the emission peak of shorter wavelength has smaller halfwidth than the other emission peak.

[0020] This makes it possible to extract long wavelength componentsrelatively easily and obtain the light emitting device that hasexcellent color rendering performance.

[0021] Moreover, the first light emitting device according to thepresent invention may have an additional fluorescent substance that hasanother emission peak between the two emission peaks that arecomplementary colors of each other.

[0022] This constitution makes the light emitting device capable ofemitting white light and also capable of emitting light of a desiredintermediate color.

[0023] The first light emitting device of the present invention may alsobe caused to emit light of a desired color by controlling thecomposition of the fluorescent substance so as to adjust the intensityratio of the two emission peaks that are complementary colors of eachother.

[0024] This allows fine adjustment of the light color in the whiteregion where human eyes can perceive even a slight difference.

[0025] A second light emitting device according to the present inventioncomprises a light emitting element and a fluorescent substance that isexcited by the light emitting element, wherein the light emittingelement has an emission spectrum in a region from ultraviolet to visiblelight of short wavelengths, and the fluorescent substance isEu-activated alkali earth metal halogen-apatite fluorescent substancethat includes at least an element selected from the group consisting ofMg, Ca, Ba, Sr and Zn and an element selected from the group consistingof Mn, Fe, Cr and Sn.

[0026] The second light emitting device of the present invention canemit white light with high luminance and can be mass producedsatisfactorily.

[0027] In the first and the second light emitting devices of the presentinvention, a nitride semiconductor that includes at least In and Ga, ora nitride semiconductor that includes at least Ga and Al can be used forthe light emitting layer of the light emitting element. This makes itpossible for the light emitting element to emit light in a regionranging from near ultraviolet to visible light of short wavelengths withhigh luminance. Also because width of the emission spectrum of the lightemitting element can be made smaller, the fluorescent substance can beexcited efficiently and changes in the color tone of the light emittedby the light emitting device can be suppressed. It goes without sayingthat the above applies to a nitride semiconductor that includes In, Gaand Al as well.

[0028] In the first and the second light emitting devices of the presentinvention, the light emitting element preferably comprises an n-typenitride semiconductor layer that includes an n-type contact layer, alight emitting layer and a p-type nitride semiconductor layer thatincludes a p-type contact layer being formed one on another, with thep-type contact layer having light transmitting p electrode made ofmetal, that includes one kind selected from the group of gold andplatinum group, covering substantially the entire surface thereof, whilethickness of the light transmitting p electrode and thickness of then-type contact layer being set so that sheet resistance Rp Ω/□ of thelight transmitting p electrode and sheet resistance Rn Ω/□ of the n-typecontact layer satisfy the relationship of Rp≧Rn.

[0029] While external quantum efficiency and emission distribution varydepending on the balance between the sheet resistance of the n-typecontact layer and sheet resistance of the light transmitting pelectrode, a light emitting element having relatively good externalquantum efficiency can be made and a light emitting device having highoutput power can be made when the relationship of Rp≧Rn is satisfied.Impurity concentrations in the contact layers are preferably in a rangefrom 10¹⁷ to 10²⁰/cm³.

[0030] In the constitution described above, sheet resistance of thelight transmitting p electrode is preferably 10 Ω/□ or higher, whichmakes it possible to easily form an n-type gallium nitride compoundsemiconductor layer having sheet resistance Rn that satisfies therelationship of Rp≧Rn.

[0031] The thickness of the light transmitting p electrode is preferablyin a range from 50 Å to 150 Å. This makes light transmittance far higherthan the case where the light transmitting p electrode is thicker than150 μm, resulting in drastically improved external quantum efficiencyand a light emitting device having high output power.

[0032] In case the light transmitting p electrode is formed from amulti-film layer, made of one kind of metal selected from a groupconsisting of gold and platinum group elements and at least one kind ofother metal, or an alloy, then sheet resistance of the lighttransmitting p electrode is preferably controlled by adjusting thecontent of gold and platinum group element. Gold and platinum groupelements have high absorptivity for light of short wavelengths, andtherefore preferably included in concentrations in a range from 20% to50% since less content leads to higher light transmittance.

[0033] Thus external quantum efficiency of the semiconductor lightemitting element of the present invention is improved and higher outputpower can be achieved by setting the sheet resistance of the n-typecontact layer and the sheet resistance of the light transmitting pelectrode so as to satisfy the relationship described above.

[0034] The first and second light emitting devices of the presentinvention also preferably have an electrode disposed in the vicinity ofat least one side of the semiconductor light emitting element on then-type contact layer and a base electrode formed at a position adjacentto the side that opposes the side in the vicinity of which the nelectrode is disposed on the light transmitting p electrode, whileextension conductors are provided along two lines being connected to thebase electrode that extends along the side of the light transmitting pelectrode on both sides thereof in the vicinity of which the baseelectrodes are located.

[0035] While there is no limitation to the shape of the base electrodeand such shapes as near rectangle and circle can be preferably used,strong emission of light occurs in the periphery of the base in case thebase electrode becomes too small. Therefore in the constitutiondescribed above, the area of emitting strong light is increased byproviding the extension conductors extending from the base electrode. Inthe n electrode, it is preferable to make the notch area of the lightemitting plane smaller in order to expose the n-type layer. Number ofthe extension conductors may be more than two.

[0036] In the constitution described above, uniform distribution oflight emission can be obtained since the n electrode is disposed near atleast one side of the light emission element and the base electrode isprovided in the vicinity of the side that opposes the side whereon the nelectrode is provided.

[0037] Moreover, in the first and second light emitting devices of thepresent invention, it is preferable that the n electrode is disposed atone corner of the semiconductor light emitting element near two sidesthereof, and the base electrode is located near the side in the vicinityof which the n electrode is located.

[0038] The extension conductors are preferably formed in an arc shape soas to be equi-distanced from the n electrode, which results in moreuniform light intensity distribution.

[0039] In the second light emitting device of the present invention, thefluorescent substance is preferably Eu-activated alkali earth metalhalogen-apatite fluorescent substance including at least Mn and/or Cl.This fluorescent substance has high light fastness and weatherability,capable of efficiently absorbing the light emitted by the nitridesemiconductor light emitting element, emit light in white region andallows it to obtain a desired emission spectrum by controlling thecomposition thereof. The fluorescent substance is also capable ofemitting yellow or red light with high luminance by absorbing nearultraviolet rays. Therefore a light emitting device having excellentcolor rendering performance can be made. The alkali earth metalhalogen-apatite fluorescent substance includes alkali earth metalchlor-apatite fluorescent substance as a matter of course.

[0040] In the second light emitting device of the present invention, thefluorescent substance may be one represented by(M_(1-x-y)Eu_(x)M′_(y))₁₀(PO₄)₆Q₂ (M represents at least one kind ofelement selected from Mg, Ca, Ba, Sr and Zn, M′ represents at least onekind of element selected from Mn, Fe, Cr and Sn, and Q represents atleast one kind of halogen element selected from F, Cl, Br and I, where0.0001≦x≦0.5 and 0.0001≦y≦0.5).

[0041] When Cl is used for Q in the formula described above, the lightemitting device can be mass-produced satisfactorily and allows colormixing of the light emitted.

[0042] The first and second light emitting devices of the presentinvention may include, in addition to the fluorescent substancedescribed above, at least one kind of fluorescent substance selectedfrom the group consisting of BaMg₂Al₁₆O₂₇:Eu, BaMgAl₁₀O₁₇:Eu,BaMgAl₁₀O₁₇:Eu, Mn, (Sr, Ca, Ba)₅(PO₄)₃Cl: Eu, (Sr, Ca, Ba)₁₀(PO₄)₆Cl₂,SrAl₂O₄:Eu, Sr₄Al₁₄O₂₅:Eu, ZnS:Cu, Zn₂GeO₄:Mn, BaMg₂Al₁₆O₂₇:Eu, Mn,Y₂O₂S:Eu, La₂O₂S:Eu and Gd₂O₂S:Eu.

[0043] This constitution achieves a light emitting device that allows itto make fine adjustment of the color tone and can emit white lighthaving high color rendering performance with relatively simpleconstitution.

[0044] The first and second light emitting devices of the presentinvention may include, in addition to the fluorescent substance, onerepresented by (M_(1-x)Eu_(x))₁₀(PO₄)₆Q₂ (M represents at least one kindof element selected from Mg, Ca, Ba, Sr and Zn, and Q represents atleast one kind of halogen element selected from F, Cl, Br and I, where0.0001≦x≦0.5 and 0.0001≦y≦0.5).

[0045] With the constitution described above, the light emitting devicecan emit white light having high color rendering performance withrelatively simple constitution in case Cl is used for Q.

[0046] A third light emitting device according to the present inventioncomprises a light emitting element and a fluorescent substance that isexcited by the light emitting element, wherein the light emittingelement has an emission spectrum in from ultraviolet to visible light ofshort wavelengths, and the fluorescent substance is alkali earth metalhalogen-apatite fluorescent substance that includes at least an elementselected from Mg, Ca, Ba, Sr and Zn and an element selected from Mn, Fe,Cr and Sn.

[0047] The third light emitting device can emit white light with highluminance and can be mass produced satisfactorily.

[0048] In the third light emitting device, the fluorescent substance ispreferably alkali earth metal halogen-apatite fluorescent substanceincluding at least Mn and/or Cl, which gives the fluorescent substancehigh light fastness and weatherability. This fluorescent substance canefficiently absorb the light emitted by the nitride semiconductor.

[0049] The first to third light emitting devices constituted asdescribed above have better luminance and mass productivity as lightsources including illumination, making use of the advantage of the lightemitting element.

[0050] Particularly, since the fluorescent substance has an excitationspectrum that is flat over a relatively broad range of wavelengths,unevenness in the color tone caused by variability in the emissionspectrum of the semiconductor light emitting element can be improved.

[0051] It is also made easier to manufacture the light emitting devicewith better mass productivity. The light emitting device also allows itto extract components of long wavelengths relatively easily whileproviding high color rendering performance.

[0052] Moreover, the light emitting device is capable of emitting whitelight, providing light of a desired intermediate color with highluminance, and allows delicate adjustment of the color tone.

[0053] A fourth light emitting device according to the present inventioncomprises a light emitting element and a fluorescent substance that isexcited by the light emitting element, wherein the light emittingelement has an emission spectrum in a region ranging from ultraviolet tovisible light of short wavelengths, and the fluorescent substanceincludes a first fluorescent substance that has an emission spectrumdifferent from that of the light emitting element and a secondfluorescent substance that has an emission spectrum different from thatof the first fluorescent substance.

[0054] This constitution improves unevenness in the color tone caused byvariability in the emission spectrum of the light emitting element.

[0055] In the fourth light emitting device of the present invention, thesecond fluorescent substance may also be excited at least one of thelight emitted by the light emitting element and light emitted by thefirst fluorescent substance.

[0056] This constitution makes it possible to use such a fluorescentsubstance, that cannot be excited by the semiconductor light emittingelement but can be excited by the light emitted by the first fluorescentsubstance, as the second high output. This constitution can alsomitigate the influence of variability of the emission spectrum of thesemiconductor light emitting element, suppress the variability inchromaticity and improve the unevenness in color tone.

[0057] In the fourth light emitting device of the present invention, itis preferable that the emission spectrum of at least one of the firstfluorescent substance and the second fluorescent substance has two ormore peaks, of which two are in the relationship of complementary colorsof each other.

[0058] This constitution can make the light emitting device having lesscolor deviation and higher color rendering performance.

[0059] The fourth light emitting device of the present invention mayalso be constituted so that the first fluorescent substance has anemission spectrum having a peak wavelength that is in the relationshipof complementary colors with the peak wavelength of the emissionspectrum of the second fluorescent substance.

[0060] This constitution allows fine adjustment of the light color inthe white region where human eyes can perceive even a slight difference.

[0061] The fourth light emitting device of the present invention is alsopreferably constituted so that the main emission wavelength of the lightemitting element is longer than 360 nm in the ultraviolet region Thisconstitution makes it possible to emit light of an intermediate colorwith high luminance.

[0062] In the fourth light emitting device of the present invention,cerium-activated fluorescent substance based on yttrium aluminum oxidemay also be used as the second fluorescent substance.

[0063] In the fourth light emitting device according to the presentinvention, the first fluorescent substance is preferably Eu-activatedalkali earth metal halogen-apatite fluorescent substance that includesat least an element selected from Mg, Ca, Ba, Sr and Zn and an elementselected from Mn, Fe, Cr and Sn.

[0064] The fluorescent substance has high light fastness andweatherability and is capable of efficiently absorbing the light emittedby the light emitting element made of nitride semiconductor.

[0065] The fluorescent substance can also emit light in white region andallows it to obtain a desired emission spectrum by controlling thecomposition thereof. The fluorescent substance is also capable ofemitting yellow or red light with high luminance by absorbing nearultraviolet rays. Therefore a light emitting device having excellentcolor rendering performance can be made by using this fluorescentsubstance. The alkali earth metal halogen-apatite fluorescent substanceincludes alkali earth metal chlor-apatite fluorescent substance, as amatter of course.

[0066] In the fourth light emitting device of the present invention, thefirst fluorescent substance is preferably a fluorescent substanceselected from the group consisting of the materials (1) to (13)described below.

[0067] (1) A fluorescent substance represented by

(M1_(1-a-b)Eu_(a)L1_(b))₁₀(PO₄)₆Q₂

[0068]  wherein M1 represents at least one element selected from Mg, Ca,Ba, Sr and Zn, L1 represents at least one element selected from Mn, Fe,Cr and Sn, and Q represents at least one halogen element selected fromF, Cl, Br and I, where 0.0001≦a≦0.5 and 0.0001≦b≦0.5.

[0069] (2) A fluorescent substance represented by

(M1_(1-a)Eu_(a))₁₀(PO₄)₆Q₂

[0070]  wherein M1 represents at least one element selected from Mg, Ca,Ba, Sr and Zn, and Q represents at least one halogen element selectedfrom F, Cl, Br and I, where 0.0001≦a≦0.5.

[0071] (3) A fluorescent substance represented by

(M1_(1-a-b)Eu_(a)Mn_(b))₁₀(PO₄)₆Q₂

[0072]  wherein M1 represents at least one element selected from Mg, Ca,Ba, Sr and Zn, and Q represents at least one halogen element selectedfrom F, Cl, Br and I, where 0.0001≦a≦0.5 and0.0001≦b≦0.5.

[0073] (4) A fluorescent substance represented by

(M2_(1-a-c)Eu_(a)Ba_(c))₁₀(PO₄)₆Q₂

[0074]  wherein M2 represents at least one element selected from Mg, Ca,Sr and Zn, and Q represents at least one halogen element selected fromF, Cl, Br and I, where 0.0001≦a≦0.5 and 0.10≦c≦0.98.

[0075] (5) A fluorescent substance represented by M1_(1-a)Eu_(a)Al₂O₄wherein M1 represents at least one element selected from Mg, Ca, Ba, Srand Zn, where 0.0001≦a≦0.5.

[0076] (6) A fluorescent substance represented by

M1_(1-a-b)Eu_(a)Mn_(b)Al₂O₄

[0077]  wherein M1 represents at least one element selected from Mg, Ca,Ba, Sr and Zn, where 0.0001≦a≦0.5 and 0.0001≦b≦0.5.

[0078] (7) A fluorescent substance represented by

M3_(1-a-c)Eu_(a)Ca_(c)Al₂O₄

[0079]  wherein M3 represents at least one element selected from Mg, Ba,Sr and Zn, where 0.0001≦a≦0.5 and 0.10≦c≦0.98.

[0080] (8) A fluorescent substance represented byM4_(1-a)Eu_(a)MgAl₁₀O₁₇ wherein M4 represents at least one elementselected from Ca, Ba, Sr and Zn, where 0.0001≦a≦0.5.

[0081] (9) A fluorescent substance represented by

M4_(1-a)Eu_(a)Mg_(1-b)Mn_(b)Al₁₀O₁₇

[0082]  wherein M4 represents at least one element selected from Ca, Ba,Sr and Zn where 0.0001≦a≦0.5 and 0.0001≦b≦0.5.

[0083] (10) A fluorescent substance represented by

(M1_(1-a)Eu_(a))₄Al₁₄O₂₅

[0084]  wherein M1 represents at least one element selected from Mg, Ca,Ba, Sr and Zn, where 0.0001≦a≦0.5.

[0085] (11) A fluorescent substance represented by ZnS:Cu

[0086] (12) A fluorescent substance represented by (Zn,Cd)S:Cu, Mn

[0087] (13) A fluorescent substance represented by Re₂O₂S:Eu wherein Rerepresents at least one element selected from Sc, Y, La, Gd and Lu.

[0088] In the fourth light emitting device of the present invention, thefirst fluorescent substance may also include at least a fluorescentsubstance represented by (M_(1-a-b)Eu_(a)L1_(b))₁₀(PO₄)₆Q₂ and one ormore fluorescent substance having composition different from thatdescribed above, and the second fluorescent substance may be afluorescent substance based on cerium-activated yttrium aluminum oxide.In the formula described above, M1 represents at least one kind ofelement selected from Mg, Ca, Ba, Sr and Zn, L1 represents at least onekind of element selected from Mn, Fe, Cr and Sn, and Q represents atleast one kind of halogen element selected from F, Cl, Br and I, where0.0001≦a≦0.5 and 0.0001≦b≦0.5.

[0089] In the fourth light emitting device of the present invention, thefirst fluorescent substance may also include a fluorescent substancerepresented by (M_(1-a-b)Eu_(a)L1_(b))₁₀(PO₄)₆Q₂ and a fluorescentsubstance represented by (M_(1-a)Eu_(b))₁₀(PO₄)₆Q₂, and the secondfluorescent substance may be a fluorescent substance based oncerium-activated yttrium aluminum oxide. In the formulas describedabove, M1 represents at least one kind of element selected from Mg, Ca,Ba, Sr and Zn, L1 represents at least one kind of element selected fromMn, Fe, Cr and Sn, and Q represents at least one kind of halogen elementselected from F, Cl, Br and I, where 0.0001≦a≦0.5 and 0.0001≦b≦0.5.

[0090] In the fourth light emitting device of the present invention, thefirst fluorescent substance may also include a fluorescent substancerepresented by (M_(1-a-b)Eu_(a)L1_(b))₁₀(PO₄)₆Q₂, a fluorescentsubstance represented by (M_(1-a)Eu_(a))₁₀(PO₄)₆Q₂ and a fluorescentsubstance represented by (M_(1-a)Eu_(a))₄Al₁₄O₂₅, and the secondfluorescent substance may be a fluorescent substance based oncerium-activated yttrium aluminum oxide. In the formulas describedabove, M1 represents at least one kind of element selected from Mg, Ca,Ba, Sr and Zn, L1 represents at least one kind of element selected fromMn, Fe, Cr and Sn, and Q represents at least one kind of halogen elementselected from F, Cl, Br and I, where 0.0001≦a≦0.5 and 0.0001≦b≦0.5.

[0091] In the fourth light emitting device of the present invention, thefirst fluorescent substance may also include a fluorescent substancerepresented by (M_(1-a-b)Eu_(a)L1_(b))₁₀(PO₄)₆Q₂, a fluorescentsubstance represented by (M_(1-a)Eu_(a))₁₀(PO₄)₆Q₂, a fluorescentsubstance represented by (M_(1-a)Eu_(a))₄Al₁₄O₂₅ and a fluorescentsubstance represented by Re₂O₂S:Eu, and the second fluorescent substancemay be a fluorescent substance based on cerium-activated yttriumaluminum oxide. In the formulas described above, M1 represents at leastone kind of element selected from Mg, Ca, Ba, Sr and Zn, L1 representsat least one kind of element selected from Mn, Fe, Cr and Sn, Qrepresents at least one kind of halogen element selected from F, Cl, Brand I, and Re represents at least one element selected from Sc, Y, La,Gd and Lu, where 0.0001≦a≦0.5 and 0.0001≦b≦0.5.

[0092] In the fourth light emitting device of the present invention, thelight emitting layer of the light emitting element may also be made of anitride semiconductor that includes at least In and Ga, or a nitridesemiconductor that includes at least Ga and Al. A light emitting elementthat includes such light emitting layer can emit light in fromultraviolet to visible light of short wavelengths with a high luminance.Also because emission spectrum of the light emitting element can be madenarrower, the fluorescent substance can be excited efficiently and thelight emitting device can emit light of spectrum having less variationin the color tone. A nitride semiconductor that includes at least In, Aland Ga is also included in the above, as a matter of course.

[0093] In the fourth light emitting device of the present invention, anexcitation spectrum that is flat over a relatively broad range ofwavelengths can be achieved by mixing the fluorescent substances thathave different emission spectra, and unevenness in the color tone causedby variability in the emission spectrum of the light emitting elementcan be improved.

[0094] Particularly since the second fluorescent substance can beexcited also by the light emitted by the first fluorescent substancethat is excited by the semiconductor light emitting element, the lightemitting device can provide better color rendering performance. It isalso made easier to manufacture the light emitting device with bettermass productivity. The fourth light emitting device also allows it toextract components of long wavelengths relatively easily while providinghigh color rendering performance. Moreover, the light emitting device iscapable of emitting white light, providing light of a desiredintermediate color with high luminance, and allows delicate adjustmentof the color tone.

BRIEF DESCRIPTION OF THE DRAWINGS

[0095]FIG. 1 is a graph showing an example of an emission spectrum ofthe light emitting device according to the first embodiment of thepresent invention.

[0096]FIG. 2A is a schematic plan view of the light emitting device(surface-mounted light emitting device) according to the firstembodiment of the present invention.

[0097]FIG. 2B is a schematic sectional view of the light emitting deviceaccording to the first embodiment of the present invention.

[0098]FIG. 3 is a chromaticity chart of CIE showing the chromaticity ofthe light emitting devices of Examples 1, 9 and 17 of the presentinvention.

[0099]FIG. 4 is a graph showing the emission spectrum of fluorescentsubstance used in Example 1 (dashed line) and in Example 9 (solid line)when excited by light of 365 nm.

[0100]FIG. 5 is a graph showing the emission spectrum of fluorescentsubstance used in Example 1 (dashed line) and Example 9 (solid line)when excited by light of 450 nm.

[0101]FIG. 6 is a graph showing the emission spectrum of fluorescentsubstance used in Example 1 (dashed line) and Example 9 (solid line)when excited by light of 590 nm.

[0102]FIG. 7 is a graph showing an Example of emission spectrum of thesemiconductor light emitting element used in the light emitting deviceof the first embodiment of the present invention.

[0103]FIG. 8 is a graph schematically showing a change in the emissionspectrum of the fluorescent substance when wavelength of light emittedby the semiconductor light emitting element changes.

[0104]FIG. 9 is a graph showing an Example of emission spectrum of thelight emitting device of the second embodiment according to the presentinvention.

[0105]FIG. 10 is a schematic sectional view of a light emitting deviceof a variation according to the present invention.

[0106]FIGS. 11A to 11E show part of manufacturing processes for thesemiconductor light emitting element used in Example 1 of the presentinvention.

[0107]FIG. 12 is a plan view of the semiconductor light emitting elementused in Example 1 of the present invention.

[0108]FIG. 13 is a plan view showing the configuration of electrodes ofthe semiconductor light emitting element used in the first embodiment ofthe present invention.

[0109]FIG. 14 is a plan view showing a configuration of electrodesdifferent from that in FIG. 13 in the semiconductor light emittingelement of the first embodiment.

[0110]FIG. 15 is a plan view showing a preferable configuration ofelectrodes of the semiconductor light emitting element used in Example1.

[0111]FIG. 16 is a plan view showing a configuration of electrodes in avariation shown in FIG. 15 of the semiconductor light emitting elementused in the first embodiment.

BEST MODE FOR CARRYING OUT THE INVENTION

[0112] Preferred embodiments of the present invention will be describedbelow.

[0113] Embodiment 1

[0114] The light emitting device according to the first embodiment ofthe present invention is constituted by the combination of:

[0115] (1) a semiconductor light emitting element that emits light of awavelength in ultraviolet region; and

[0116] (2) a fluorescent substance including at least one kind offluorescent substance (first fluorescent substance) that is excited byultraviolet rays emitted by the light emitting element and has anemission spectrum having two peaks that are complementary colors of eachother,

[0117] so as to provide the light emitted by the fluorescent substanceto the outside.

[0118] The light emitting device of the first embodiment having such aconstitution as described above is hardly affected by the variability inthe emission wavelength of the light emitting element as will beexplained later, and the color of the emitted light is determined onlyby the emission spectrum of the fluorescent substance. Accordingly, sucheffects can be achieved as less variability in chromaticity, suitabilityto mass production and reliability that are much higher than in theprior art.

[0119] Specifically, in the light emitting device of the firstembodiment, as shown schematically in FIG. 8, even when the emissionwavelength of light emitting element that excites the first fluorescentsubstance changes by Δλ, chromaticity undergoes less variability sinceintensity ratio between two peaks hardly changes, though the intensityof the emission spectrum may change as a whole.

[0120] Therefore, light emitting device of the first embodiment does notshow deviation in the chromaticity even when the emission wavelength ofthe light emitting element varies.

[0121] In the light emitting device of the prior art that produces adesired color by mixing the light emitted by a light emitting elementand the light emitted by a fluorescent substance, in contrast, since thevariability in the emission wavelength of the light emitting element hasdirect influence on the chromaticity of the light emitting device, lightemitted by the light emitting device shows deviation in chromaticity.

[0122] In particular, since a semiconductor light emitting element isformed by a process such as MOCVD method, even devices that are producedfrom the same wafer are subjected to variability that is much largercompared to the variability in the emission spectrum of the fluorescentsubstance. As a result, a light emitting device that directly utilizesthe light emitted by the semiconductor light emitting element may showsignificant variability.

[0123] In case the light emitted by the light emitting element is inultraviolet region and visible region of extremely low visualsensitivity (for example, wavelengths below 420 nm) as in the case ofthe first embodiment, chromaticity of the light emitting device is lesssubject to adverse influence even when the light emitted by the lightemitting element is directly output to the outside.

[0124] Since the light emitting device according to the first embodimentof the present invention uses the first fluorescent substance that isexcited by ultraviolet rays and has an emission spectrum that has twopeaks which are complementary colors of each other, variability inchromaticity can be made extremely small.

[0125] The light emitting device of the first embodiment can bemanufactured with high yield (suited to mass production) sincevariability in the light emitting elements can be accommodated so as tominimize the variation in the chromaticity.

[0126] Moreover, the light emitting device of the first embodiment alsohas high reliability, since the wavelength of light emitted thereby doesnot change even when the emission wavelength of the light emittingelement changes by aging.

[0127] Furthermore, as will be shown by way of Example later, the lightemitting device of the first embodiment allows it to control thecomposition of the fluorescent substance in accordance to the targetvalue of chromaticity, and the color tone can be easily adjusted.

[0128] Also as will be described later, light of a color tone thatbetter represent the desired one can be produced, by using an additionalfluorescent substance that has an emission peak at a wavelength betweenthose of the two peaks, for example.

[0129] Now specific constitution of the light emitting device of thefirst embodiment will be described in more detail below with referenceto FIG. 2. The light emitting device of the first embodiment is a lightemitting device of surface mount type as shown in FIG. 2. The lightemitting device of the first embodiment uses a nitride semiconductorlight emitting element (LED chip) that has an InGaN light emitting layerof such a composition that emits light with peak intensity at about 370nm, as a light emitting element, as shown in FIG. 7. The LED chipcomprises an n-type GaN layer made of an undoped nitride semiconductor,an Si-doped GaN layer serving as n-type contact layer for forming ann-type electrode, an n-type GaN layer made of an undoped nitridesemiconductor, an n-type AlGaN layer made of a nitride semiconductor, anInGaN layer of single quantum well structure serving as a light emittinglayer, an AlGaN layer that is an Mg-doped p-type cladding layer and aGaN layer that is an Mg-doped p-type cladding layer, formed one onanother on a sapphire substrate. In the first embodiment, a buffer layeris formed on the sapphire substrate by growing a GaN layer at a lowtemperature in advance, and the p-type semiconductor is changed top-type by annealing at a temperature of 400° C. or higher after formingthe film. In this LED chip, a part of the n-type contact layer surfaceis exposed by etching on the same side as the p-type contact layer, anda strip of n-type electrode is formed on the exposed n-type contactlayer, while a light transmitting p-type electrode made of a thin metalfilm is formed over substantially the entire surface of the p-typecontact layer. Moreover a base electrode is formed on the lighttransmitting p-type electrode in parallel to the n-type electrode bysputtering process.

[0130] In the light emitting device of the first embodiment, a package 5comprises a base made of Kovar that has a recess at the center thereofto accommodate the LED chip 1, and lead electrodes 2 made of Kovarinserted in through holes 3 formed on both sides of the recess of thebase. The lead electrode 2 is provided in the through hole 3 of the basewhile being insulated from the base made of Kovar by means of aninsulating sealing material that also provides hermetic sealing. AnNi/Ag layer is formed on the surfaces of the package 5 and the leadelectrode 2. The LED chip 1 is die-bonded by means of Ag—Sn alloy in therecess of the package 5 that is constituted as described above. Withthis constitution, all constituent members of the light emitting devicecan all be made of inorganic substances, so that the light emittingdevice can have dramatically improved reliability even when lightemitted by the LED chip 1 is in the ultraviolet region or in the visiblelight region of short wavelengths.

[0131] The electrodes of the LED chip 1 that are die-bonded areelectrically connected by means of Ag wires 4 to the lead electrodes 2that are exposed to the bottom surface of the package base. The lightemitting device of the first embodiment is sealed with a lid 6 made ofKovar that has a glass window 7 at the center. The lid 6 made of Kovarand the package base are hermetically sealed by seam welding after fullypurging the moisture from the recess of the package 5. A slurryincluding 90% by weight of nitrocellulose, 10% by weight of γ-aluminaand a fluorescent substance 8 is applied to the inside of the glasswindow 7 of the lid 6 made of Kovar, and is hardened by heating at 220°C. for 30 minutes so as to form a color conversion member 80 in advance.

[0132] According to the first embodiment, various fluorescent substancesto be described later can be used.

[0133] The light emitting device (light emitting diode) of the firstembodiment having such a constitution as described above is capable ofemitting white light with a high luminance.

[0134] In case alkali earth metal chlor-apatite fluorescent substanceactivated with Eu including at least Mn (first fluorescent substance)(Sr_(0.96), Eu_(0.01), Mn_(0.08))₁₀(PO₄)₆Cl₂ and SrAl₂O₄:Eu fluorescentsubstance, for example, are used as the fluorescent substance 8 in thefirst embodiment, the light emission characteristic shown in FIG. 1 isobtained.

[0135] The peak at wavelength of about 460 nm and the peak at wavelengthof about 580 nm shown in FIG. 1 are the peaks of emission by (Sr_(0.96),Eu_(0.01), Mn_(0.08))₁₀(PO₄)₆Cl₂ fluorescent substance that haverelationship of complementary colors of each other. Emission around 520nm shows the spectrum of emission by SrAl₂O₄:Eu. In this example, thedesired chromaticity is approximately achieved by means of the(Sr_(0.96), Eu_(0.01), Mn_(0.08))₁₀(PO₄)₆C that has the two emissionpeaks, and the chromaticity is adjusted by means of the SrAl₂O₄:Eufluorescent substance that is a green fluorescent substance tocompensate for the lack of green shade, thereby making the chromaticitynearer to that desired.

[0136] Thus the light emitting device of this Example can minimize thevariability in chromaticity by using the first fluorescent substancethat has two emission peaks and very easily control the chromaticity byusing the second fluorescent substance, so that the devices of highreliability can be favorably mass produced.

[0137] Now the constitution of the light emitting device according tothe first embodiment will be described below. (Semiconductor lightemitting element) For the semiconductor light emitting element of thepresent invention, a semiconductor light emitting element that has alight emitting layer capable of emitting light of such a wavelength thatcan efficiently excite the fluorescent substance is used.

[0138] Such a semiconductor light emitting element may be made ofvarious semiconductor materials such as BN, SiC, ZnSe, GaN, InGaN,InAlGaN, AlGaN, BalGaN and BinAlGaN. Any of these materials may also becomplemented with an impurity element such as Si or Zn as luminescencecenter. As a material for light emitting layer that can emit lightefficiently in a region from ultraviolet to visible light of shortwavelengths for efficiently excite the fluorescent substance, nitridesemiconductors (for example, In_(x)Al_(y)Ga_(1-X-Y)N, 0≦X, 0≦Y, X+Y≦1)for nitride semiconductor including Al and/or Ga, and nitridesemiconductor) are particularly suitable.

[0139] The semiconductor light emitting element may be constituted inhomojunction structure that has MIS junction, PIN junction or pnjunction, heterojunction structure or double heterojunction structure.Emission wavelength of the semiconductor material can be controlled soas to match the excitation wavelength of the fluorescent substance byadjusting the composition of mixed crystal. Output power can beincreased by forming the active layer in single quantum well structureor multiple quantum well structure.

[0140] When the light emitting element is made of a nitridesemiconductor, the substrate can be made of sapphire, spinel, SiC, Si,ZnO, GaAs or GaN. In order to form the nitride semiconductor with goodcrystallinity and characteristic suitable for mass production, it ispreferable to use a sapphire substrate. The nitride semiconductor can beformed on the sapphire substrate by the HVPE process, MOCVD process orthe like. It is more preferable to form the nitride semiconductor thathas pn junction on a buffer layer that is not a single crystal and isformed on the sapphire substrate by growing GaN, AlN, GaAlN or the likeat a low temperature.

[0141] A light emitting element of double heterojunction structure madein a procedure described below mat be used as an Example of lightemitting element that is made of a nitride semiconductor and canefficiently emit light in the ultraviolet region.

[0142] First, a buffer layer is formed on the sapphire substrate, and anSiO₂ layer is formed in stripe pattern on the buffer layer atsubstantially right angles to the orientation flat plane of the sapphiresubstrate.

[0143] Then a GaN layer of ELOG (Epitaxial Lateral Over Growth GaN) isformed on the stripe by the HVPE method.

[0144] Then a first contact layer made of n-type gallium nitride, afirst cladding layer made of n-type aluminum gallium nitride, an activelayer of multiple quantum well structure consisting of a plurality ofwell layers made of indium aluminum gallium nitride and barrier layersmade of aluminum gallium nitride formed one on another, a secondcladding layer made of p-type aluminum gallium nitride and a secondcontact layer made of p-type gallium nitride stacked in this order.

[0145] The p-type layer is etched so as to expose a part of the n-typecontact layer surface, and electrodes are formed on the p-type andn-type contact layers, followed by the separation of individual chip,thus making the LED chips.

[0146] With this constitution, the active layer can be formed in a ridgestripe pattern sandwiched by guide layers with a resonator end facebeing provided, so as to make a semiconductor laser element that can beused in the present invention.

[0147] The nitride semiconductor shows n-type conductivity when notdoped with an impurity. However, since it is necessary to control theconcentration of a desired carrier to a predetermined value, it ispreferable to introduce Si, Ge, Se, Te, C or the like as n-type dopantin order to form the n-type nitride semiconductor. When a p-type nitridesemiconductor is formed, on the other hand, the semiconductor is dopedwith Zn, Mg, Be, Ca, Sr, Ba or the like as p-type dopant. At this time,since it is difficult to turn the nitride semiconductor into p-typesimply by doping with a p-type dopant, it is preferable to decrease theresistivity by heating in a furnace or plasma irradiation afterintroducing the p-type dopant.

[0148] In the semiconductor light emitting element used in the presentinvention, sheet resistance of the n-type contact layer formed withimpurity concentration in a range from 10¹⁷ to 10²⁰/cm³ and sheetresistance of the light transmitting p electrode are preferablycontrolled to satisfy the relationship of Rp≧Rn. The n-type contactlayer is formed to a thickness of preferably from 3 to 10 μm, morepreferably from 4 to 6 μm. As the sheet resistance of the n-type contactlayer is estimated at 10 to 15 Ω/□, the thin film is preferably formedso that the sheet resistance Rp is not less than the value describedabove. The light transmitting p electrode may also be formed in a thinfilm having thickness of 150 Å or less.

[0149] In case the light transmitting p electrode is formed from amulti-film layer, made of one kind of metal selected from a groupconsisting of gold and platinum group elements and at least one kind ofother metal, or an alloy, then stability and reproducibility can beimproved by controlling the content of gold or platinum group elementthereby to regulate the sheet resistance of the light transmitting pelectrode. Since gold or the other metal element has a high absorptivityin the wavelength region of the semiconductor light emitting elementthat is used in the present invention, the transmittance becomes higherwhen the light transmitting p electrode includes less gold or platinumgroup element. The semiconductor light emitting element of the prior arthas the relation of Rp≦Rn for the sheet resistances. Since Rp≧Rn holdsaccording to the present invention, the light transmitting p electrodeis formed with smaller thickness than in the prior art, the thicknesscan be decreased easily by reducing the content of gold or the othermetal element.

[0150] In the semiconductor light emitting element used in the presentinvention, as described above, sheet resistance Rn Ω/□ of the n-typecontact layer and sheet resistance Rp Ω/□ of the light transmitting pelectrode are preferably controlled to satisfy the relationship ofRp≧Rn. It is difficult to measure the value of Rn after making thesemiconductor light emitting element, and it is virtually impossible toknow the relationship between Rp and Rn. Although the relationshipbetween Rp and Rn can be estimated from the light intensity distributionduring emission.

[0151] A p-side base electrode is formed on a part of the lighttransmitting p electrode that is formed over substantially the entiresurface of the p-type contact layer.

[0152] Preferable arrangement of the electrodes according to the presentinvention will be described below with reference to FIG. 13 to FIG. 16.

[0153] In the light emitting element of the present invention, an nelectrode 53 is disposed in the vicinity of at least one side of thesemiconductor light emitting element, as shown in FIG. 13 and FIG. 14.In the Example shown in FIG. 13 and FIG. 14, a part of the p-type layerand a part of the active layer are removed by etching in the middleportion of the one side so as to provide a notch 51 a where the n-typecontact layer 51 is exposed, and the n electrode 53 is formed in thenotch 51 a.

[0154] The p-side base electrode 55 is formed at a position adjacent tothe side that opposes the side in the vicinity of which the n electrodeis disposed in the light transmitting p electrode 54. An extensionconductor 56 on two lines are connected to the p base electrode 55, theextension conductors 56 extending along the side in the vicinity ofwhich the base electrodes 55 on both sides. According to the presentinvention, as the p-side base electrode 55 and the n electrode 53 areformed in the positional relationship described above, the active layerdisposed between the p-side base electrode 55 and then electrode 53 canbe caused to emit light with high efficiency. Moreover, current can beeffectively diffused throughout the p layer by forming the extensionconductor 56 that is connected to the p-side base electrode 55 so as tohave electrical continuity on the light transmitting p electrode 54, sothat the light emitting layer emits light efficiently as a whole.

[0155] Also it has been confirmed by the present inventors that light isemitted with high luminance in the portion around the extensionconductor 56 and the p-side base electrode 55.

[0156] According to the present invention, therefore, it is morepreferable to effectively utilize the light emitted with high luminancein the portion around the extension conductor 56.

[0157] Specifically, in order to secure the peripheral portion thatemits light with high luminance between the extension conductor 56 andthe edges of the light emitting layer and the p layer along which theextension conductor 56 is formed, it is preferable to keep a spacebetween the edge and the extension conductor 56. When sheet resistanceRn Ω/□ of the n-type contact layer and sheet resistance Rp Ω/□ of thelight transmitting p electrode 54 satisfy the relationship of Rp≧Rn, thespace between the extension conductor 56 and the edge of the lightemitting layer is preferably from 20 μm to 50 μm. When the space is lessthan 20 μm, the peripheral portion that emits light with high luminancecannot be secured (the region that should emit light with high luminanceextends to the outside). When the space is larger than 50 μm, a portionthat emits light with low luminance is formed along the adjacent side,leading to a low luminance as a whole.

[0158] The extension conductors 56 is preferably formed in an arc shapeso as to be equi-distanced from the n electrode 53 as shown in FIG. 13,which results in more uniform light intensity distribution than in acase of forming the extension conductors 56 in a straight configurationas shown in FIG. 14.

[0159] Moreover, according to the present invention, it is morepreferable that the n electrode 63 is located at one corner of thesemiconductor light emitting element near two sides, and the baseelectrode is located at a corner diagonally opposite to the corner nearwhich the n electrode 63 is located.

[0160] In case the n electrode 63 and the p-side base electrode 65 aredisposed diagonally opposite to each other, too, the extensionconductors 66 are preferably formed in an arc shape so as to beequi-distanced from the n electrode 63 as shown in FIG. 15 and FIG. 16,which makes it possible to emit light with higher luminance and higheruniformity.

[0161] The space between the extension conductor 66 and the edge of thelight emitting layer is preferably from 20 μm to 50 μm, in order tosecure the region where light is emitted with high luminance, asmentioned previously.

[0162] The light emitting device of the present invention is preferablymade of a resin for the purpose of mass production. In this case, whenconsidering the wavelength of light emitted by the fluorescent substanceand degradation of the light transmitting resin, it is preferable thatthe light emitting element emits light in ultraviolet region with peakwavelength in a range from 360 to 420 nm, more preferably from 370 to410 nm. In order to further improve the excitation and light emissionefficiencies of the light emitting element and the fluorescentsubstance, the peak wavelength is more preferably in a range from 380 to400 nm.

[0163] (Fluorescent Substance 8)

[0164] While the light emitting device of the first embodiment uses thefluorescent substance that can be excited by the light emitted by thesemiconductor light emitting element and efficiently emit light ofwavelengths different from that of the excitation light is used, afluorescent substance of which excitation region includes ultravioletregion is preferably used in the first embodiment. Also in the firstembodiment, the fluorescent substance includes the first fluorescentsubstance that absorbs at least a part of the light emitted by thesemiconductor light emitting element of wavelengths longer than 360 nmin the ultraviolet region, and emit light of spectrum having two or moreemission peaks. At least two of the two or more emission peaks of thefirst fluorescent substance are preferably complementary colors of eachother. Moreover, one of the two emission peaks of the first fluorescentsubstance that are complementary colors of each other is the largestemission peak of the emission spectrum and the other peak has anintensity of 50% of the largest emission peak or more. Furthermore,either one of the two emission peaks that are complementary colors ofeach other preferably includes red component. Specifically, afluorescent substance that satisfies the requirements described aboveis, for example, alkali earth metal halogen-apatite fluorescentsubstance activated with Eu that includes at least Mn and/or Cl.

[0165] The fluorescent substance can be prepared by a process describedbelow. First, phosphate oxide that is a component of the fluorescentsubstance or a compound that can turn into the oxide through thermolysisand ammonium chloride are weighed and mixed in a ball mill or the like.The mixed material is put into a crucible and is fired in reducingatmosphere of N₂ or H₂ at a temperature from 800 to 1200° C. for 3 to 7hours. The fired material is crushed in a wet process, sieved,dehydrated and dried thereby to obtain the alkali earth metalhalogen-apatite fluorescent substance.

[0166] According to the present invention, alkali earth metalhalogen-apatite fluorescent substance represented by general formula(M_(1-x-y)Eu_(x)M′_(y))₁₀(PO₄)₆Q₂ (M represents at least one kind ofelement selected from Mg, Ca, Ba, Sr and Zn, M′ represents at least onekind of element selected from Mn, Fe, Cr, Sr and Zn, and Q represents atleast one kind of halogen element selected from F, Cl, Br and I). Inthis case, the proportion x of the first activation element Eu in thegeneral formula described above is preferably in a range from0.0001≦x≦0.5. This is because the luminance of light emitted becomeslower when the value of x is less than 0.0001, the luminance of emissiontends to decrease due to concentration optical quenching when the valueof x is larger than 0.5. Value of x is more preferably in a range of0.005≦x≦0.4, and further more preferably in a range of 0.01≦x≦0.2.

[0167] In the general formula described above, y is the proportion of atleast one kind of element selected from Mn, Fe, Cr and Sn. The value ofy is preferably in a range from 0.0001≦x≦0.5, more preferably in a rangeof 0.005≦x≦0.4, and further more preferably in a range of 0.01≦x≦0.3.The luminance of emission tends to decrease due to concentration opticalquenching when the value of y is larger than 0.5.

[0168] The fluorescent substance emits visible light from blue, white(for example, white color specified in JIS Z8110 or white color that isbasic color of systematic color chart) to red color when excited byirradiation in a region ranging from ultraviolet to visible light ofshort wavelengths (for example, light of main wavelength not longer than440 nm).

[0169] In particular, since the alkali earth metal halogen-apatitefluorescent substance described above can be efficiently excited also byultraviolet rays of relatively long wavelengths around 365 nm so as toemit light with high luminance that also includes red component, goodcolor rendering performance can be achieved with mean color renderingindex Ra of 80 or higher.

[0170] The CIE chromacity chart of FIG. 3 shows the colors of lightemitted by the fluorescent substances, that are used in the first, ninthand seventeenth embodiments to be described later, excited by lighthaving wavelength of 365.5 nm. It can be seen from FIG. 3 that colortone can be controlled from blue, white to red by changing thecomposition of the fluorescent substance used in the first embodiment.

[0171] When Sr is used as the element M, blue light is emitted by Eu²⁺that has a peak of emission at around 450 nm, while the color of lightemitted by the fluorescent substance changes from blue, white to red dueto the emission by Mn, as the value of y is increased for the proportionof M′ that is Mn. While similar changes are observed depending on theproportions of Eu and Mn also in case Ca is used as M, emitted lightundergoes less changes in case Ba is used as M.

[0172] Dashed line in FIG. 4 shows the emission spectrum of thefluorescent substance used in the first embodiment when excited withlight of 365 nm, dashed line in FIG. 5 shows the emission spectrum ofthe fluorescent substance used in Example 1 when excited with light of450 nm, and dashed line in FIG. 6 shows the emission spectrum of thefluorescent substance used in the first embodiment when excited withlight of 590 nm. From FIG. 6, it can be seen that the fluorescentsubstance used in the present invention is efficiently excited withlight in a region ranging from near ultraviolet to visible light ofrelatively short wavelengths (for example, from 230 or 300 nm to 400 or425 nm), and the emitted light belongs to a region identified as basiccolor of white in JIS Z8110. This fluorescent substance is excitedefficiently by any light in the entire ultraviolet region, and istherefore expected to be used effectively for excitation with shortwavelength ultraviolet.

[0173] Solid line in FIG. 4 shows the emission spectrum of thefluorescent substance used in Example 9 when excited with light of 365nm. It can be seen that the fluorescent substance used in the ninthembodiment has a relatively broad emission spectrum with peaks at about460 nm and about 600 nm.

[0174] Solid line in FIG. 5 shows the emission spectrum of thefluorescent substance used in Example 9 when excited with light of 460nm, and solid line in FIG. 6 shows the emission spectrum of thefluorescent substance used in Example 9 when excited with light of 600nm.

[0175] A light emitting device that uses this fluorescent substance canemit light with emission spectrum that has peaks at about 460 nm andabout 580 nm, upon excitation by light emitted by an ultraviolet LED oran ultraviolet LD. The component of wavelength around 460 nm and thecomponent of wavelength around 580 nm in this emission spectrum arecomplementary colors of each other. According to the present invention,color rendering performance can be improved further by adding SrAl₂O₄:Eu that is a green light emitting fluorescent substance to alkali earthmetal halogen-apatite fluorescent substance activated with Eu thatincludes at least Mn and/or Cl.

[0176] In addition to Eu, one kind selected from Tb, Cu, Ag, Au, Cr, Nd,Dy, Co, Ni and Ti may be included in the fluorescent substance asrequired.

[0177] Particle size of the fluorescent substance is preferablycontrolled in a range from 1 to 100 μm, more preferably in a range from5 to 50 μm. Furthermore preferable range is from 10 to 30 μm. Thefluorescent substance having particle sizes less than 10 μm isrelatively more prone to coagulation. Light absorptivity and conversionefficiency of the fluorescent substance can be improved and thebandwidth of excitation light can be increased by controlling theparticle size within the range described above. Thus use of thefluorescent substance of large particle size that has better opticalcharacteristics makes it possible to emit light by efficientlyconverting the light of wavelengths around the peak wavelength of thelight emitting element, and also improve the mass productivity of thelight emitting device because coagulation can be prevented.

[0178] The particle size referred to herein is represented by a valuedetermined from volumetric particle size distribution curve. Thevolumetric particle size distribution curve is obtained by measuring theparticle size distribution by laser diffraction and diffusion method.Specifically, the fluorescent substance is dispersed in an aqueoussolution of sodium hexametaphosphate of 0.05% concentration at ambienttemperature of 25° C. and humidity of 70%, and a laser diffractionparticle size distribution measuring instrument (SALD-2000A) is used tomeasure in a range from 0.03 μm to 700 μm. Medium particle size refersto the particle size of 50 percentile value of the volumetric particlesize distribution curve. The fluorescent substance of the presentinvention can emit light with high luminance since the median particlesize in set in a range from 15 μm to 50 μm. According to the presentinvention, it is preferable that a higher proportion of the fluorescentsubstance having the median particle size described above is included,with the proportion being preferably from 20% to 50%. By using thefluorescent substance having less variability in the particle sizes,color unevenness can be minimized and a light emitting device havingsatisfactory color tone can be obtained.

[0179] Embodiment 2

[0180] The light emitting device according to the second embodiment ofthe present invention will now be described below.

[0181] The light emitting device of the second embodiment is constitutedin the same manner as in the first embodiment, except for using thefluorescent substance that is different from that of the firstembodiment.

[0182] The light emitting device of the second embodiment emits lightwith less color deviation by taking advantage of the fact that thebandwidth of blurred light emitted by the fluorescent substance uponexcitation by the light emitting element is less than the bandwidth ofblurred light emitted by the light emitting element

[0183] While the semiconductor light emitting element is formed by theMOCVD or other process, some variability occur even among chips that areproduced from a same wafer. As a result, a light emitting device thatoutputs the light emitted by the semiconductor light emitting elementtends to produce very large variability. The light emitting device ofthe second embodiment has been completed upon finding the fact thatvariability in the wavelength of light emitted by the light emittingelement can be absorbed by a fluorescent substance to be describedlater, in case the light emitting element having emission spectrum in aregion ranging from ultraviolet rays to visible region of extremely lowvisual sensitivity (for example, wavelengths below 420 nm) is used.

[0184] Specifically, the light emitting device of the second embodimenthas a first fluorescent substance that is excited by the semiconductorlight emitting element and a second fluorescent substance that has adifferent emission spectrum from those of the first fluorescentsubstance and the semiconductor light emitting element. Thisconstitution makes it possible to suppress the variability in thewavelength of the emitted light and emit light with better colorrendering performance. In the light emitting device of the secondembodiment, two fluorescent substances provide two or more peaks ofemission as shown in FIG. 9, so that deviation in the color tone oflight emitted by the fluorescent substance can be minimized anddeviation in the color tone of light emitted by the light emittingdevice can be suppressed. In the light emitting device of the secondembodiment, it is preferable that at least two of the two or more peaksof the emission spectrum of the fluorescent substance are complementarycolors of each other, which allows it to minimize the deviation in thecolor tone of light emitted by the fluorescent substance and suppressthe deviation in the color tone of light emitted by the light emittingdevice. As the second fluorescent substance is excited by the lightemitted by the first fluorescent substance, stable light with furtherreduced color deviation can be emitted. This effect is achievedsupposedly because the second fluorescent substance is excited by thelight having less variability emitted by the first fluorescent substancethat is excited by the semiconductor light emitting element, therebyachieving the stable light emitting device that has less colordeviation.

[0185] Also by using two or more kinds of fluorescent substances as inthe case of the second embodiment, it is made easier to control thecolor tone of the light emitting device so that, for example, deviationin color tone can be suppressed by using additional fluorescentsubstance that has another peak between the two peaks of the emissionspectrum that are complementary colors to each other.

[0186] Now the fluorescent substance used in the light emitting deviceof the second embodiment will be described in more detail below.

[0187] (Fluorescent Substance)

[0188] The fluorescent substance used in the light emitting device ofthe second embodiment comprises the first fluorescent substance that canefficiently emit light when excited by the light emitted by thesemiconductor light emitting element, and the second fluorescentsubstance that has an emission spectrum different from those of thefirst fluorescent substance and the semiconductor light emittingelement. The second fluorescent substance may also be a fluorescentsubstance that can emit light upon excitation by the first fluorescentsubstance. Although each of the first fluorescent substance and thesecond fluorescent substance can be used individually, the lightemitting device of excellent color rendering performance is made byusing both the first fluorescent substance and the second fluorescentsubstance in the second embodiment. Therefore, the fluorescent substancehereinafter mentioned includes fluorescent substances that can beindividually used with satisfactory effects. In the light emittingdevice of the second embodiment, the first fluorescent substance and thesecond fluorescent substance can efficiently utilize the light that isapplied as the respective excitation source. In addition, since twokinds of light emitted by the two fluorescent substances are mixed, thelight emitting device has excellent color rendering performance.

[0189] The first fluorescent substance and the second fluorescentsubstance may each be a single material or comprise two or more kinds ofmaterial. This increases the combinations of emission spectra, therebymaking it possible to achieve the light emitting device having excellentcharacteristics such as color rendering performance and luminance ofemitted light, by selecting a proper combination. Moreover, in casethose combined are complementary colors of each other, white color canbe produced efficiently. In case the second fluorescent substance isexcited by the light emitted by the first fluorescent substance and thefirst fluorescent substance is constituted from two or more components,it is not necessary for all components of the first fluorescentsubstance to be used as the excitation source of the second fluorescentsubstance, and it suffices that any one component of the firstfluorescent substance can excite the second fluorescent substance. Thesecond fluorescent substance may be such that can be excited by both thesemiconductor light emitting element and the first fluorescentsubstance.

[0190] Regardless of whether the first fluorescent substance and thesecond fluorescent substance are each constituted from one component ortwo or more components, the first fluorescent substance and the secondfluorescent substance can emit light of colors that are complementarycolors of each other. This constitution makes the light emitting devicehaving better color rendering performance. With this constitution, colorunevenness can be suppressed better than in case only one of the firstfluorescent substance and the second fluorescent substance isconstituted from two or more components to produce complementary colors.When the first fluorescent substance is constituted from two componentsto produce complementary colors, for example, degradation of one of thecomponents due to heat degradation leads to unbalanced color tone,resulting in the color tone changing over time. This holds true also incase the second fluorescent substance is constituted from two componentsto produce complementary colors. When the first fluorescent substanceand the second fluorescent substance emit light of colors that arecomplementary colors of each other and the second fluorescent substanceis excited by the light emitted by the first fluorescent substance, incontrast, degradation of the first fluorescent substance results in lessexcitation of the second fluorescent substance and hence less colordeviation, though output power and efficiency of light emissiondecrease.

[0191] (First Fluorescent Substance)

[0192] According to the second embodiment, the first fluorescentsubstance preferably has an excitation spectrum in a region at leastfrom ultraviolet to visible light of short wavelengths. It is alsopreferable that the first fluorescent substance can emit light byabsorbing at least part of the light emitted by the semiconductor lightemitting element that has an emission spectrum ranging from nearultraviolet of wavelengths longer than 360 nm to visible light of shortwavelengths, and the emission spectrum has two or more peaks at leasttwo of which are complementary colors of each other. The firstfluorescent substance may also be constituted from two or more kinds offluorescent substance that have different emission spectra. with thisconstitution, it is made possible to mix the light of not only thesemiconductor light emitting element but also the fluorescentsubstances. A fluorescent substance preferably .used as the firstfluorescent substance is alkali earth metal halogen-apatite fluorescentsubstance including at least an element represented by M1 selected fromMg, Ca, Ba, Sr and Zn and an element represented by L1 selected from Mn,Fe, Cr and Sn.

[0193] Specifically, the following materials may be used.

[0194] A fluorescent substance represented by(M1_(1-a-b)Eu_(a)L1_(b))₁₀(PO₄)₆Q₂;

[0195] A fluorescent substance represented by(M1_(1-a)Eu_(a))₁₀(PO₄)₆Q₂;

[0196] A fluorescent substance represented by(M1_(1-a-c)Eu_(a)Mn_(b))₁₀(PO₄)₆Q₂;

[0197] A fluorescent substance represented by(M2_(1-a-b)Eu_(a)Ba_(c))₁₀(PO₄)₆Q₂;

[0198] A fluorescent substance represented by M1_(1-a)Eu_(a)Al₂O₄;

[0199] A fluorescent substance represented byM1_(1-a-b)Eu_(a)Mn_(b)Al₂O₄;

[0200] A fluorescent substance represented byM3_(1-a-c)Eu_(a)Ca_(c)Al₂O₄;

[0201] A fluorescent substance represented by M4_(1-a)Eu_(a)MgAl₁₀O₁₇;

[0202] A fluorescent substance represented byM4_(1-a)Eu_(a)Mg_(1-b)Mn_(b)Al₁₀O₁₇;

[0203] A fluorescent substance represented by (M1_(1-a)Eu_(a))₄Al₁₄O₂₅;

[0204] A fluorescent substance represented by ZnS:Cu;

[0205] A fluorescent substance represented by (Zn,Cd)S:Cu, Mn; and

[0206] A fluorescent substance represented by Re₂O₂S:Eu.

[0207] In the formulas described above, M1 represents at least oneelement selected from Mg, Ca, Ba, Sr and Zn, M2 represents at least oneelement selected from Mg, Ca, Sr and Zn, M3 represents at least oneelement selected from Mg, Ba, Sr and Zn, M4 represents at least oneelement selected from Ca, Ba, Sr and Zn, L1 represents at least oneelement selected from Mn, Fe, Cr and Sn, Re represents at least oneelement selected from Sc, Y, La, Gd and Lu, and Q represents at leastone halogen element selected from F, Cl, Br and I.

[0208] In the general formulas described above, value of a that presentsthe proportion of the first activation agent Eu is preferably in a rangeof 0.0001≦a≦0.5. This is because the luminance of emitted light becomestoo low when the value of a is less than 0.0001, and the luminance ofemission tends to decrease due to concentration optical quenching whenthe value of a is larger than 0.5. In order to prevent the luminance ofemitted light from decreasing more effectively, the value of a is morepreferably in a range of 0.005≦a≦0.4, and further more preferably in arange of 0.01≦a≦0.2. Also the value of b that represents the proportionof at least one kind of element selected from Mn, Fe, Cr and Sn ispreferably in a range from 0.0001≦b≦0.5, more preferably in a range of0.005≦b≦0.4, and further more preferably in a range of 0.01≦b≦0.3. Theluminance of emission tends to decrease due to concentration opticalquenching when the value of b is larger than 0.5.

[0209] When these materials are used as the first fluorescent substanceexcited by the light emitted by the semiconductor light emitting elementhaving main peak around 400 nm, light of the following colors is output.

[0210] Blue light from (M1_(1-a)Eu_(a))₁₀(PO₄)₆Q₂ andM3_(1-a-c)Eu_(a)Ca_(c)Al₂O₄, M4_(1-a)Eu_(a)MgAl₁₀O₁₇

[0211] Bluish green light from by (M1_(1-a)Eu_(a))₄Al₁₄O₂₅ and(M2_(1-a-b)Eu_(a)Ba_(c))₁₀(PO₄)₆Q₂

[0212] Green light from M4_(1-a)Eu_(a)Mg_(1-b)Mn_(b)Al₁₀O₁₇,M1_(1-a)Eu_(a)Al₂O₄ and ZnS: Cu

[0213] Amber light from (Zn,Cd)S:Cu, Mn

[0214] Red light from Re₂O₂S:Eu

[0215] White light from (M1_(1-a-b)Eu_(a)L1_(b))₁₀(PO₄)₆Q₂,(M1_(1-a-c)Eu_(a)Mn_(b))₁₀(PO₄)₆Q₂ and M1_(1-a-b)Eu_(a)Mn_(b)Al₂O₄

[0216] The light emitting device of the second embodiment uses thesecond fluorescent substance in addition to the semiconductor lightemitting element and the first fluorescent substance. In case afluorescent substance based on YAG is used as the second fluorescentsubstance, (M1_(1-a-b)Eu_(a)L1_(b))₁₀(PO₄)₆Q₂, emits white light.

[0217] (M1_(1-a-b)Eu_(a)L1_(b))₁₀(PO₄)₆Q₂ used as the first fluorescentsubstance is excited by light of wavelength of about 400 nm emitted bythe semiconductor light emitting element so as to emit light includingred component. Therefore, when the light emitting device is constitutedfrom the first fluorescent substance and the semiconductor lightemitting element, white light with strong red shade is emitted and whitelight having excellent color rendering performance can be produced byadding YAG fluorescent substance.

[0218] This fluorescent substance can be prepared by the processdescribed below. Phosphate oxide that is a component of the fluorescentsubstance or a compound that can turn into the oxide through thermolysisand ammonium chloride are weighed and mixed in a ball mill. The mixedmaterial is put into a crucible and is fired in a reducing atmosphere ofN₂ or H₂ at a temperature from800 to 1200° C. for 3 to 7 hours. Thefired material is crushed in a wet process, sieved, dehydrated and driedthereby to obtain the alkali earth metal halogen-apatite fluorescentsubstance.

[0219] The fluorescent substance emits visible light from blue, white(for example, white color specified in JIS Z8110 or white color that isbasic color of systematic color chart) to red color when excited by fromultraviolet to visible light of short wavelengths.

[0220] In particular, since the fluorescent substance described abovecan be efficiently excited also by ultraviolet rays of relatively longwavelengths around 400 nm so as to emit light with high luminance thatalso includes red component, good color rendering performance can beachieved with mean color rendering index Ra of 80 or higher.

[0221] The light emitting device of the second embodiment can providehigher color rendering performance by using the first fluorescentsubstance that is excited by the semiconductor light emitting element soas to emit light and the second fluorescent substance that has adifferent emission spectrum from those of the first fluorescentsubstance and the semiconductor light emitting element.

[0222] (Second Fluorescent Substance)

[0223] In the light emitting device of the second embodiment, the secondfluorescent substance has an emission spectrum that is different fromthose of both the first fluorescent substance and the semiconductorlight emitting element. The excitation source may be either thesemiconductor light emitting element or the first fluorescent substance,or both the semiconductor light emitting element and the firstfluorescent substance.

[0224] In case the second fluorescent substance can emit light uponexcitation by the semiconductor light emitting element in the samemanner as in the first fluorescent substance, there is no need todistinguish between the first fluorescent substance and the secondfluorescent substance. In the second embodiment, however, thefluorescent substance that can be excited by the first fluorescentsubstance that emits light through excitation by the semiconductor lightemitting element is distinguished by a different name from the firstfluorescent substance for convenience.

[0225] When the semiconductor light emitting element is used as theexcitation light source, fluorescent substances that can emit light byusing this excitation light source are limited since the excitationlight source has narrow half width. There is also such a drawback ofpoor color rendering performance when used for illumination as a whitelight source. When a semiconductor light emitting element capable ofemitting blue light and a fluorescent substance that emits light ofcomplementary color are used and the blue light emitted by the lightemitting element and the yellow light emitted by the fluorescentsubstance are mixed, white light can be produced. While white light canbe produced by mixing the blue light emitted by the light emittingelement and the yellow light emitted by the fluorescent substance, theresultant light lacks red shade and therefore has poor color renderingperformance when used for illumination, since the mixed light does notcontain red component.

[0226] The light emitting device of the second embodiment, in contrast,can drastically improve the color rendering performance by using thesecond fluorescent substance as well as the first fluorescent substance.The second fluorescent substance is preferably capable of being excitedby the light emitted by the semiconductor light emitting element, in thesame manner as in the first fluorescent substance, so as to emit lightefficiently. A fluorescent substance that is excited by the lightemitted by the first fluorescent substance may also be used. In thiscase, efficient emission of light can be achieved by using the main peakof the first fluorescent substance as the emission light source.However, since the first fluorescent substance has broader half widththan the semiconductor light emitting element does, emission spectrum ofthe first fluorescent substance is broader than the sharp emissionspectrum of the semiconductor light emitting element. Therefore, thesecond fluorescent substance may also be excited by the light emitted bythe first fluorescent substance of wavelength other than that of themain peak.

[0227] The second fluorescent substance can be excited either by thelight emitted by the semiconductor light emitting element or by thelight emitted by the first fluorescent substance. White light havingreddish component and excellent color rendering performance can beemitted by using the semiconductor light emitting element capable ofemitting blue light and a fluorescent substance that can emit red light,for example (CaEuMn)₁₀(PO₄)₆Cl₂, as the first fluorescent substance soas to compensate for white light that lacks reddish component emitted bythe YAG fluorescent substance excited by the semiconductor lightemitting element.

[0228] Cerium-activated fluorescent substance based on yttrium aluminumoxide may be used as the second fluorescent substance. Specifically,YAlO₃:Ce, Y₃Al₅O₁₂:Ce(YAG:Ce), Y₄Al₂O₉:Ce or a mixture of thesematerials may be used. Moreover, the second fluorescent substance mayalso include at least one element selected from Ba, Sr, Mg, Ca and Zn.Si may also be added so as to restrain the crystal growth in order toobtain uniform particles of the fluorescent substance.

[0229] In this specification, the term “cerium-activated fluorescentsubstance based on yttrium aluminum oxide” should be interpreted in abroad sense to include such fluorescent substance of which part or allof yttrium atoms are substituted with an element selected from a groupconsisting of Lu, Sc, La, Gd and Sm or part or all of aluminum atoms aresubstituted with an element selected from a group consisting of Ba, Tl,Ga and In.

[0230] More specifically, a photoluminescence fluorescent substancerepresented by general formula (Y₂Gd_(1-z))₃Al₅O₁₂:Ce (0<z≦1) or aphotoluminescence fluorescent substance represented by general formula(Re_(1-a)Sm_(a))₃Re′₅O₁₂:Ce (0≦a<1, 0≦b≦1, wherein Re is at least oneelement selected from Y, Gd, La and Sc, and Re′ is at least one elementselected from Al, Ga and In) is used.

[0231] This fluorescent substance is highly durable against heat, lightand moisture due to garnet structure, and can have peak of excitationspectrum at a wavelength around 450 nm. The emission spectrum also has abroad peak around 580 nm tailing to 700 nm.

[0232] The photoluminescence fluorescent substance includes Gd(gadolinium) in the crystal, and therefore efficiency of light emissionupon excitation in a wavelength region longer than 460 nm can be madehigher. When the content of Gd is increased, wavelength of the emissionpeak shifts to a longer wavelength with the entire emission spectrumalso shifting to longer wavelengths. Accordingly, when light of reddishcolor is desired, it can be produced by heavily substituting with Gd. Asthe content of Gd increases, luminance of photoluminescence by bluelight tends to decrease. In addition to Ce, such elements as Tb, Cu, Ag,Au, Fe, Cr, Nd, Dy, Co, Ni, Ti and Eu may be added.

[0233] Emission wavelengths of the fluorescent substance based onyttrium aluminum garnet oxide having garnet structure shifts towardshorter wavelengths when part of Al atoms are substituted with Ga.Emission wavelengths shifts toward longer wavelengths when part of Yatoms are substituted with Gd.

[0234] When part of Y atoms are substituted with Gd, it is preferable torestrict the proportion of Y atoms are substituted with Gd less than10%, and control the content of Ce in a range from 0.3 to 1.0. Althoughgreen component become predominant and red component diminishes when theproportion of Y atoms substituted with Gd is less than 20%, shortage ofred component can be made up by increasing the Ce content and desiredcolor tone can be achieved without decreasing luminance. Temperaturecharacteristic can be improved with this composition, and reliability ofthe light emitting device can be improved. A light emitting device thatcan emit light of an intermediate color such as pink can be made byusing photoluminescence fluorescent substance that is made in such aconstitution that emits light with much red component.

[0235] Such a photoluminescence fluorescent substance can be made in aprocedure described below. First, oxides of Y, Cd, Al and Ce, orcompounds that can easily turn into the oxides at a high temperature aremixed in stoichiometrical proportions. Or, alternatively, acoprecipitated oxide obtained by coprecipitation, with oxalic acid, asolution prepared by dissolving a rare earth element such as Y, Gs or Cein stoichiometrical proportion in an acid, and firing the coprecipitateand aluminum oxide are mixed. This mixture is mixed with a fluoride suchas barium fluoride or ammonium fluoride as a flux. The mixed material isput into a crucible and is fired in air at a temperature from 1350 to1450° C. for 2 to 5 hours. The fired material is processed with a ballmill in water, washed, separated, dried and sieved.

[0236] According to the second embodiment, the photoluminescencefluorescent substance used as the second fluorescent substance may be amixture of two or more kinds of fluorescent substance based on yttriumaluminum garnet oxide activated with cerium.

[0237] Preferable ranges of particle sizes of the first fluorescentsubstance and the second fluorescent substance are similar to thosedescribed in conjunction with the first embodiment, and the reason forsetting in the range is also the same.

[0238] The method of measuring the particle size is also the same asthat of the first embodiment.

[0239] In the second embodiment, a slurry including 90% by weight ofnitrocellulose and 10% by weight of γ-alumina mixed with, for example,(Ca_(0.96)Eu_(0.01)Mn_(0.03))₁₀(PO₄)₆Cl₂ as the first fluorescentsubstance and (YAG: Ce) activated with cerium as the second fluorescentsubstance is applied to the inside of the glass window of the lid, andis hardened by heating at 220° C. for 30 minutes so as to form a colorconversion member in advance.

[0240] Variations

[0241] While light emitting devices according to the preferredembodiments of the present invention have been described, variousmodifications as described below can be made according to the presentinvention.

[0242] In the present invention, the position where the fluorescentsubstance is disposed may be selected from many candidates while givingconsideration to the relative position with the light emitting elementand the constitution of the light emitting element.

[0243] In the first and second embodiments, the color conversion member80 is formed on the inside of the window 7. The color conversion member80 may also be formed on the side face of the recess of the package 5 asshown in FIG. 10. In this case, the p-side ohmic electrode of the LEDchip 1 does not have translucency and is constituted so as to reflectthe light emitted by the light emitting layer back into thesemiconductor and let the light emerge from the side face of the LEDchip 1.

[0244] Also such a constitution may be employs as the fluorescentsubstance is included in the die bonding material used for die boding ofthe light emitting element, or the fluorescent substance is included inthe molding material that covers the light emitting element.

[0245] Thus according to the present invention, the fluorescentsubstance may be disposed either separately from the light emittingelement or directly on the light emitting element.

[0246] In the first and second embodiments, the color conversion member80 is formed from nitrocellulose. However, the present invention is notlimited to this constitution, and the color conversion member includingthe fluorescent substance can be from various binders including a resinthat is an organic material and glass that is an inorganic material.When an organic material is used as the binder, transparent resins thathave high weatherability such as epoxy resin, acrylic resin and siliconeare preferably used. Silicone is particularly preferable due to highreliability and capability to improve the characteristic to disperse thefluorescent substance.

[0247] An inorganic material may also be used as the binder. In thiscase, precipitation process or sol-gel process may be employed. Forexample, a slurry is formed by mixing the fluorescent substance, silanol(Si(OEt)₃OH) and ethanol, with the silanol discharged through a nozzleis heated at 300° C. for 3 hours to turn into SiO₂, thereby to have thefluorescent substance deposited at a desired place. In order to applythe fluorescent substance to the window, it is preferable to use aninorganic material that has a thermal expansion coefficient similar tothat of the window material, which allows secure bonding of thefluorescent substance onto the window.

[0248] An inorganic bonding material may also be used as the binder. Thebonding material is low-melting point glass, that is preferably madefrom fine particles and is very stable with low absorptivity to lightranging from ultraviolet to visible light. These requirements aresatisfied by borate made from alkali earth element in the form of fineparticles obtained by precipitation.

[0249] In case a fluorescent substance having large particle size isapplied, it is preferable to use a bonding material that has a highmelting point and can be turned into ultra-fine powder, for example,pyrophosphate or normal phosphate made from silica, alumina or alkaliearth element in the form of fine particles obtained by precipitation.These bonding materials may be used alone or in combination.

[0250] Method for applying the bonding material will be described below.For the bonding material, it is preferable to use a slurry made bydispersing the bonding material that has been crushed in a wet processin a vehicle, in order to ensure high bonding effect. The vehicle refersto a high viscosity solution made by dissolving a small amount ofbinding agent in an organic solvent or deionized water. For example, anorganic vehicle is made by adding 1% by weight of nitrocellulose as thebinding agent to butyl acetate that is used as the organic solvent.

[0251] The fluorescent substance is added to the slurry of bondingmaterial obtained as described above, thereby to make the applicationliquid. While the bonding agent is added in proportion of 1 to 3% byweight of the quantity of fluorescent substance in the applicationliquid, it is preferable to add smaller quantity of bonding agent inorder to prevent the luminous flux retaining ratio from decreasing. Theapplication liquid prepared as described above is applied to the backsurface of the window. This film is then dried by blowing warm air orhot air. Last, the film is baked at a temperature from 400 to 700° C.,so as to evaporate the vehicle thereby forming the fluorescent substancelayer as the color conversion member bonded at the desired place bymeans of the bonding agent.

[0252] (Diffusing Agent)

[0253] Further according to the present invention, a diffusing agent maybe added to the fluorescent substance. For the diffusing agent, bariumtitanate, titanium oxide, aluminum oxide, silicon oxide or the like ispreferably used. This makes it possible to obtain a light emittingdevice having good directivity.

[0254] The diffusing agent has median particle size in a range from 1 nmto 5 μm. The diffusing agent of median particle size in a range from 1μm to 5 μm reflects light from the fluorescent substance randomly, andis capable of suppressing color unevenness that is apt to result fromthe use of fluorescent substance having larger particle sizes. Thediffusing agent of size in a range from 1 μm to 5 μm, in contrast, canincrease the viscosity of resin without decreasing the luminousintensity, although the effect of interfering with the light emitted bythe light emitting element is lower. Thus when the resin including thefluorescent substance is applied by potting or the like, it is madepossible to disperse the fluorescent substance included in the resinuniformly in a syringe and maintain this condition, so that the lightemitting device can be manufactured with a high yield even when thefluorescent substance of larger particle sizes that is difficult tohandle. The diffusing agent according to the present invention hasdifferent effects depending on the particle size, as described above,and can be selected and used in combination according to theapplication.

[0255] (Filler)

[0256] According to the present invention, the color conversion membermay include a filler in addition to the fluorescent substance. Thefiller is made of a material similar to the diffusing agent but hasmedian particle size different from that of the diffusing agent. In thisspecification, the filler refers to a material having of median particlesize in a range from 1 μm to 5 μm. When the filler of this particle sizeis included in the light transmitting resin, variability in thechromaticity of the light emitting devices is improved by the lightdiffusion effect, and resistance of the light transmitting resin againstthermal shock can also be improved. As a result, such troubles can beprevented as the wires connecting the light emitting element withexternal electrodes break and the light emitting element comes off therecess of the package even when used at high temperatures, therebyproviding the light emitting device of high reliability. Moreover, it ismade possible to maintain constant fluidity of the resin for a longperiod of time, so that the sealing member can be formed at the desiredplace and mass-produce the light emitting devices with high yield.

[0257] The filler preferably has particle size and/or particle shapesimilar to those of the fluorescent substance. In this specification,similar particle size means that difference between the median particlesizes of two materials is less than 20%, and similar particle shapemeans that difference between the values of roundness of the particlethat indicates the proximity of the particle shape to true sphere(roundness=length of circumference of true circle of area equal to theprojection area of the particle/length of circumference of theprojection area of the particle) is less than 20%. Use of such a fillercauses the fluorescent substance and the filler to act on each other, sothat the fluorescent substance is satisfactorily dispersed in the resinthereby suppressing color unevenness.

[0258] Median particles sizes of the fluorescent substance and thefiller are both controlled, for example, in a range from 15 μm to 50 μmor more preferably in a range from 20 μm to 50 μm. When the particlesizes are controlled in this range, the particles can be dispersed withproper distance from each other. As a result, paths for extracting lightcan be secured and directivity can be improved while suppressing thedecrease in luminous intensity caused by mixing the filler.

[0259] In the present invention, the light emitting device may furthercontains the fluorescent substances represented by the following generaformulas (1) to (6).

[0260] In the formulas (1) to (6), Rf1, Rf2, Rf3, Rf4 and Rf5 are thesame or different and each represents a C₁-C₂₂ aliphatic group having nohydrogen atom, an aromatic group having no hydrogen atom, or aheterocyclic group having no hydrogen atom.

[0261] Example of the C₁-C₂₂ aliphatic group having no hydrogen atominclude straight-chain or branched perhalogenated alkyl group such asperfluoroalkyl group (C_(n)F_(2n+1); n=1 to 22) or perchloroalkyl group(C_(n)Cl_(2n+1); n=1 to 22), specifically trichloromethyl,trifluoromethyl, perchloroethyl, pentafluoroethyl, heptachloropropyl,heptafluoropropyl, heptachloroisopropyl, heptafluoroisopropyl,nonachlorobutyl, nonafluorobutyl, nonachloroisobutyl,nonafluoroisobutyl, undecachloropentyl, undecafluoropentyl,undecachloroisopentyl, undecafluoroisopentyl, tridecachlorohexyl,tridecafluorohexyl, tridecachloroisohexyl, tridecafluoroisohexyl,pentadecachloroheptyl, pentadecafluoroheptyl, pentadecachloroisoheptyl,pentadecafluoroisoheptyl, heptadecachlorooctyl, heptadecafluorooctyl,heptadecachloroisooctyl, heptadecafluoroisooctyl, nonadecachlorononyl,nonadecafluorononyl, nonadecachloroisononyl, nonadecafluoroisononyl,heneicosachlorodecyl, heneicosafluorodecyl, heneicosachloroisodecyl,heneicosafluoroisodecyl, tricosachloroundecyl, tricosafluoroundecyl,tricosachloroisoundecyl, tricosafluoroisoundecyl,pentacosachlorododecyl, pentacosafluorododecyl,pentacosachloroisododecyl, pentacosafluoroisododecyl,heptacosachlorotridecyl, heptacosafluorotridecyl,heptacosachloroisotridecyl, or heptacosafluoroisotridecyl;

[0262] straight-chain or branched C₂-C₂₂ perhalogenated alkenyl groupsuch as perfluoroalkenyl group (perfluorovinyl group, perfluoroallylgroup, or perfluorobutenyl group) or perchloroalkenyl group, preferablytrifluoroethynyl, trichloroethynyl, pentafluoropropenyl,perchloropropenyl, heptafluorobutenyl, or heptachlorobutenyl;

[0263] straight-chain or branched C₂-C₂₂ perhalogenated alkynyl groupsuch as perfluoroalkynyl group or perchloroalkynyl group;

[0264] C₃-C₂₂ perhalogenated cycloalkyl group such asperfluorocycloalkyl group (C_(n)F_(2n−1); n=3 to 22, preferably 3 to 8,and more preferably 3 to 6) or perchlorocycloalkyl group(C_(n)Cl_(2n−1); n=3 to 22, preferably 3 to 8, and more preferably 3 to6), preferably perchlorocyclopropyl, pentafluorocyclopropyl,heptachlorocylobutyl, heptafluorocylobutyl, nonachlorocyclopentyl,nonafluorocyclopentyl, undecachlorocyclohexyl, undecafluorocyclohexyl,tridecachlorocycloheptyl, tridecafluorocycloheptyl,pentadecachlorocyclooctyl, or pentadecafluorocyclooctyl;

[0265] C₃-C₂₂, preferably C₃-C₈, and more preferably C₃-C₆perhalogenated cycloalkenyl group such as perfluorocycloalkenyl group(perfluorocyclopentenyl group or perfluorocyclohexenyl group) orperchlorocycloalkenyl group; and

[0266] perhalogenated aralkyl group such as perfluorobenzyl group orperfluorophenethyl group.

[0267] Example of the aromatic group in the aromatic group having nohydrogen atom include phenyl, naphthyl, anthranyl, phenanthryl, andpyrenyl.

[0268] Example of the heterocyclic group in the heterocyclic grouphaving no hydrogen atom include pyridyl, thienyl, pyronyl, pyrimidinyl,quinolyl, isoquinolyl, benzimidazoyl, benzopyranyl, indolyl,benzofuranyl, imidazolyl, pyrazolinyl, and biphenyl, and all hydrogenatoms of these aromatic groups and heterocyclic groups are substitutedwith substituents having no hydrogen atom, for example, halogen atomsuch as fluorine atom, chlorine atom or bromine atom, nitro group, C₁-C₄perhalogenated alkyl group (trifluoromethyl), C₁-C₄ perhalogenatedalkoxy group (trifluoromethoxy), C₂-C₅ perhalogenated alkylcarbonylgroup (trifluoroacetyl), C₁-C₄ perhalogenated alkylenedioxy group(difluoromethylenedioxy), C₂-C₅ perhalogenated alkenyl group(perhalogenated vinyl), perhalogenated phenoxy group, or C₂-C₂₂perhalogenated alkylcarbonyloxy. Specific Example of the aromatic grouphaving no hydrogen atom include perfluorophenyl group, perchlorophenylgroup, perfluoronaphthyl group, perchloronaphthyl group,perfluoroanthranyl group, perchloroanthranyl group, perfluorophenanthrylgroup, and perchlorophenanthryl group, while specific Example of theheterocyclic group having no hydrogen atom include perhalogenated2-pyridyl group.

[0269] One, or two or more halogen atoms attached to the aromatic ringor heterocycle of the perhalogenated aromatic group, perhalogenatedheterocyclic group and perhalogenated aralkyl group may be substitutedwith substituents having no hydrogen atom, such as cyano, nitro,nitroso, C₁-C₄ perhalogenated alkoxy, C₂-C₅ perhalogenatedalkoxycarbonyl, and C₂-C₂₂ perhalogenated alkylcarbonyloxy.

[0270] Also an ether, ester or ketone structure may be formed by makingone or a plurality of O—, —COO— and —CO— to exist between C—C singlebonds at arbitrary positions of the C₁-C₂₂ perhalogenated alkyl group,C₂-C₂₂ perhalogenated alkenyl group and C₂-C₂₂ perhalogenated alkynylgroup.

[0271] Example of the rare earth element represented by M includelanthanoid elements such as La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho,Er, Tm, Yb, and Lu, and preferably Nd, Eu, Tb, and Yb.

[0272] X1 and X2 represent an atom of the group IVA such as C, Si, Ge,Sn, or Pb, or an atom of the group VIA excluding oxygen, such as S, Se,Te, or Po, preferably C, S, P or Se, and more preferably C or S.

[0273] X3 represents an atom of the group IVA such as Si, Ge, Sn, or Pb,an atom of the group VA excluding nitrogen such as P, As, Sb, or Bi, oran atom of the group VIA excluding oxygen, such as S, Se, Te, or Po, andpreferably S.

[0274] Y represents C-Z′ (Z′ is as defined above), N, P, As, Sb or Bi,and preferably C-Z′ (Z′ is as defined above), N or P.

[0275] Z′ represents deuterium, a halogen atom, or a C₁-C₂₂ aliphaticgroup having no hydrogen atom, and preferably deuterium or astraight-chain or branched C₁-C₂₂ perhalogenated alkyl group.

[0276] Z″ represents H or Z′.

[0277] n1 represents 2 or 3, and preferably 3.

[0278] n2 represents 2 to 4, preferably 2 or 3, and particularly 3.

[0279] n3, n4 and n5 represent 0 or 1. When X1, X2 or X3 is s, n3, n4 orn5 is preferably 1. When X1 or X2 is C, n3 or n4 is 0.

[0280] The fluorescent substances represented by the formulas (1) to (6)are added to the in the light emitting device of the first embodiment,and may also be as the first fluorescent substance and the secondfluorescent substance of the light emitting element of the secondembodiment.

[0281] Examples of the present invention will be described below.

EXAMPLE 1

[0282] In Example 1, a surface-mounted light emitting device as shown inFIG. 2 is produced. The LED chip 1 has a light emitting layer that isconstituted from a nitride semiconductor made of InAlGaN semiconductorhaving an emission peak at 375 nm in the ultraviolet region. The LEDchip 1 is made by flowing TMG (trimethyl gallium) gas, TMI (trimethylindium) gas, nitrogen gas and dopant gas together with a carrier gasonto a sapphire substrate that has been washed, so as to form a nitridesemiconductor film by MOCVD process. At this time, layers of n-typenitride semiconductor and p-type nitride semiconductor are formed byswitching the dopant gas between SiH₄ and Cp₂Mg.

[0283] The LED chip 1 is made in multiple quantum well structure havingsuch a constitution as five sets of layers are stacked on the sapphiresubstrate, one set consisting of an n-type GaN layer made of an undopednitride semiconductor, a GaN layer serving as n-type contact layer forforming an Si-doped n-type electrode, an n-type GaN layer made of anundoped nitride semiconductor, an AlGaN layer including Si for making ann-type cladding layer, an AlInGaN layer of constituting well layer toserve as a light emitting layer, and an AlInGaN layer that makes abarrier including more Al content than the well layer. Formedsuccessively on the light emitting layer are an Mg-doped p-type claddinglayer made of AlGaN, a GaN layer used to increase the electrostaticwithstanding voltage and a GaN layer that is an Mg-doped p-type claddinglayer. The sapphire substrate has a buffer layer formed thereon bygrowing a GaN layer at a low temperature. The p-type semiconductor isannealed at a temperature of 400° C. or higher after forming the film.

[0284] More detailed description will be given below with reference toFIGS. 11A to 11E. FIGS. 11A to 11E show the processes of manufacturingthe semiconductor light emitting element. To manufacture thesemiconductor light emitting element, an SiO₂ film 30 that makes anetching mask is formed on the sapphire substrate 10 as shown in FIG.11A.

[0285] Then a photo mask having shape of equilateral triangle measuring10 μm on each side is placed so that one side of the triangle isperpendicular to the orientation flat plane. With the three sides of thetriangle arranged to be substantially parallel to (1-100) plane, (01-10)plane and (−1010) plane, namely the M plane of the sapphire, the SiO₂film 30 and the sapphire substrate 10 are etched about 1 μm by RIEprocess as shown in FIG. 11B and FIG. 11C. Then as the SiO₂ film 30 isremoved as shown in FIG. 11D, a repetitive pattern of recess 20 isformed on the surface of the sapphire substrate 10.

[0286] The bar (-) in the plane identification described above should beinterpreted as a bar placed above the subsequent numeral.

[0287] Then after forming the buffer layer made of GaN on the sapphiresubstrate to a thickness of 200 Å at 500° C., an undoped GaN layer isformed to a thickness of 5 μm by setting the temperature to 1050° C.Thickness of the film to be grown is not limited to 5 μm, but ispreferably controlled to a thickness within 10 μm, larger than that ofthe buffer layer. Then after growing the undoped GaN layer, the wafer istaken out of the reaction vessel, and a photo mask of stripeconfiguration is formed on the surface of the GaN layer. Then a maskmade of SiO₂ having stripes 15 μm in width and spaced at 5 μm from eachother is formed to a thickness of 0.1 μm with a CVD apparatus. Afterforming the mask, the wafer is put in the reaction vessel again to growan undoped GaN layer 10 μm thick at 1050° C. While crystal defectdensity of the undoped GaN layer is 10¹⁰/cm² or higher, crystal defectdensity of the GaN layer is 10⁶/cm² or higher.

[0288] (n-Type Contact Layer, n-Type Gallium Nitride CompoundSemiconductor Layer)

[0289] Then the n-type contact layer and the n-type gallium nitridecompound semiconductor layer are formed. The n-type contact layer madeof GaN doped with 4.5×10¹⁸/cm³ of Si is formed to a thickness of 2.25 μmat 1050° C. by using TMG gas, ammonia gas and silane gas as the impuritygas. Then with the supply of silane gas stopped, the undoped GaN layeris formed to thickness of 75 Å at 1050° C. by using TMG gas and ammoniagas, followed by the formation of 25 Å thick GaN layer doped with4.5×10¹⁸/cm³ of Si by adding silane gas at the same temperature. Thuslayer A made of undoped GaN having thickness of 75 Å and layer B made ofSi-doped GaN having thickness of 25 Å. 25 sets of these layers areformed one on another to a total thickness of 2500 Å, thereby to formthe n-type gallium nitride compound semiconductor layer consisting ofmulti-layer film of super lattice structure.

[0290] (Active Layer)

[0291] Then the barrier layer made of undoped GaN having thickness of250 Å is formed, followed by the formation of well layer made of undopedInGaN having thickness of 30 Å by using TMG, TMI and ammonia with thetemperature being set to 800° C. Seven barrier layers and six welllayers are formed alternately in the order of barrier layer+welllayer+barrier layer+well layer+ . . . +barrier layer, thereby formingthe active layer having multiple quantum well structure to a totalthickness of 1930 Å.

[0292] (p-Type Layer)

[0293] Then the p-type layer consisting of a p-side multi-layer claddinglayer and a p-type contact layer is formed. The third nitridesemiconductor layer made of p-type Al_(0.2)Ga_(0.8)N doped with1×10²⁰/cm³ of Mg is formed to a thickness of 40 Å at 1050° C. by usingTMA, ammonia and Cp₂Mg (cyclopentadienyl magnesium). Then with thetemperature being set to 800° C., the fourth nitride semiconductor layermade of In_(0.03)Ga_(0.97)N doped with 1×10²⁰/cm³ of Mg is formed to athickness of 25 Å by using TMG, TMI, ammonia and Cp₂Mg. These operationsare repeated so as to form the third layer and the fourth layer, eachfive layers, in this order with the third nitride semiconductor layer of40 Å formed on the top, thereby forming the p-side multi-layer claddinglayer having super lattice structure consisting of multi-layer film to atotal thickness of 365 Å. Then the p-type contact layer made of p-typeGaN doped with 1×10²⁰/cm³ of Mg having thickness of 700 Å is formed byusing TMG, ammonia and Cp₂Mg at 1050° C.

[0294] After the completion of the reaction, the temperature is loweredto the room temperature and the wafer is annealed at 700° C. in nitrogenatmosphere of a reaction vessel thereby to decrease the resistivity ofthe p-type layer.

[0295] Since the GaN lattice grows with an offset of 30 degrees from thesapphire substrate 10, the repetitive pattern of the recesses 20 formedon the sapphire substrate 10 becomes a polygon that has sidessubstantially parallel to A plane (11-20), (1-210) and (−2110) plane ofthe GaN, and apexes on the stable growth plane (1-100), (01-10), (−1010)but does not have straight lines parallel to the stable growth plane(1-100), (01-10), (−1010), namely M planes.

[0296] Then the p-type and n-type contact layers are exposed on the sameside of the nitride semiconductor on the sapphire substrate by etching.Specifically, a mask of predetermined configuration is formed on thesurface of the wafer that has been taken out of the reaction vessel, andthe n-type gallium nitride compound semiconductor layer is etched withan RIE (reactive ion etching) apparatus thereby to expose the surface ofthe n-type contact layer.

[0297] (Light Transmitting p Electrode, Base Electrode, n Electrode)

[0298] Positive and negative base electrodes are formed on the contactlayers by sputtering process. The p-type nitride semiconductor has,after forming a thin metal film as the light transmitting electrode overthe entire surface thereof, the base electrode formed on a part of thelight transmitting electrode. Specifically, after etching, the lighttransmitting p electrode (Ni/Au=60/50) having thickness of 110 Å isformed so as to cover substantially the entire surface of the p-typelayer, and the base electrode that is made Au with thickness of 0.5 μmand has three extension conductors is formed on the p electrode alongthe sizes at the corner of the light emitting element. Formed on then-type contact layer that has been exposed by etching is the n electrodethat includes W and Al so as to oppose the base electrode.

[0299] Then in order to form the n electrode, an area extending from theMg-doped GaN, the p-type semiconductor layer and the active layer to apart of the n-type semiconductor layer is etched so as to expose theSi-doped GaN layer.

[0300] A photo mask, having such a pattern as equilateral trianglesmeasuring 5 μm on each side are arranged side by side to fill out thespace as shown in FIG. 12, is used to form the light transmitting pelectrodes made of Ni/Au having the shape of equilateral triangle so asto cover substantially the entire surface of the p-type semiconductorlayer.

[0301] Further on the light transmitting p electrodes, p pad electrodesmade of Pt/Au are formed at a position opposing the exposed surface ofthe n-type semiconductor layer, while n electrodes made of Ti/Al and npad electrodes made of Pt/Au are formed on the exposed surface of then-type semiconductor layer

[0302] Last, the wafer is cut into rectangular chips thereby to obtainthe semiconductor light emitting element.

[0303] The semiconductor light emitting element thus obtained hasimproved output of light emission since the peripheral area of the pelectrode emits light with higher intensity than the other area.

[0304] In another embodiment, processing of the substrate and formationof layers from the n-type semiconductor layer to the p-typesemiconductor layer are carried out in the same manner as in the above.

[0305] Then in order to form the n electrode, an area extending from theMg-doped GaN, the p-type semiconductor layer and the active layer to apart of the n-type semiconductor layer is etched so as to expose theSi-doped GaN layer.

[0306] A photo mask, having such a pattern as equilateral trianglesmeasuring 5 μm on each side are arranged side by side to fill out thespace as shown in FIG. 12, is used to form the p electrodes 104 made ofRh having the shape of equilateral triangle so as to cover substantiallythe entire surface of the p-type semiconductor layer.

[0307] Further on the p electrodes 104, a p pad electrodes 105 made ofPt/Au are formed at a position opposing the exposed surface of then-type semiconductor layer, while n electrodes made of Ti/Al and n padelectrodes 103 made of Pt/Au are formed on the exposed surface of then-type semiconductor layer

[0308] Last, the wafer is cut into rectangular chips thereby to obtainthe semiconductor light emitting element. Top view of the light emittingelement is shown in FIG. 12.

[0309] The semiconductor light emitting element thus obtained hasfurther increased output of light emission since the peripheral area ofthe p electrode emits light with higher intensity than the other area,and a material of higher reflectivity to the emitted light is used forthe electrode thereby mitigating the absorption of light in theelectrode.

[0310] As a casing for the light emitting device, such a package made ofKovar is used that comprises a base having a recess at the center andlead electrodes made of Kovar are fastened on both sides of the recessand are electrically insulated and hermetically sealed. Ni/Al layer isprovided on the surfaces of the package and the lead electrodes.

[0311] The LED chip is die-bonded in the recess of the package that isconstituted as described above, by using Ag—Sn alloy. The electrodes ofthe LED chip that has been die-bonded are electrically connected with Agwires to the lead electrodes that are exposed from the bottom of therecess of the package.

[0312] Then the fluorescent substance is prepared by mixing SrHPO₄,SrCO₃, Eu₂O₃, MnCO₃ and NH₄Cl, in such proportions that correspond tothe composition of (Sr_(0.96),Eu_(0.01),Mn_(0.03))₁₀(PO₄)₆Cl₂. (SrHPO₄:1000 g, SrCO₃: 482.4 g, Eu₂O₃: 16.0 g, MnCO₃: 35.2 g, NH₄Cl: 116.5 g)

[0313] The materials are weighed and well mixed in a mixer such as ballmill in a dry process. The mixed material is put into a crucible made ofSiC, quartz or alumina and is fired in reducing atmosphere of N₂ or H₂at 1200° C. for 3 hours after raising the temperature to 1200° C. at arate of 960° C./hr. The fired material is crushed in water, dispersed,sieved, separated, washed in water and dried thereby to obtain power ofthe desired fluorescent substance.

[0314] The fluorescent substance prepared as described above and SiO₂ asfiller or diffusing agent are added to a slurry including 90% by weightof nitrocellulose and 10% by weight of γ-alumina. The slurry is appliedto the back surface of the light transmitting window of the lid, and ishardened by heating at 220° C. for 30 minutes so as to form the colorconversion member. After completely purging moisture from the recess ofthe package, the light emitting device is completed by sealing therecess with the lid made of Kovar that has a glass window at the centerthereof and applying seam welding. The chromaticity coordinates of thelight emitting device can be set to (x, y)=(0.384, 0.332).

COMPARATIVE EXAMPLE 1

[0315] A light emitting device is produced in the same manner as inExample 1, except for mixing BaMg₂Al₁₆O₂₇:Eu that emits blue light,BaMg₂Al₁₆O₂₇:Eu:Mn that emits green light and Y₂O₂S:Eu that emits redlight, instead of the fluorescent substance of the present invention, inorder to obtain the same chromaticity, using 100% of the material thatprovides the same chromaticity as Example 1, for the purpose ofluminance of light emission. The light emitting device of Example 1using excitation at 400 nm shows luminance of about 237% that ofComparative Example 1. The light emitting device using excitation at 365nm emits white light having reddish shade showing luminance of about157% that of Comparative Example 1.

[0316] In Examples 2 to 17, light emitting devices were produced in thesame manner as in Example 1, except for replacing the fluorescentsubstances of Example 1 with the fluorescent substances shown in Table1.

[0317] The results are shown in Table 2. TABLE 1 Examples Fluorescentsubstances 1 (Sr_(0.96), Eu_(0.01), Mn_(0.03))₁₀(PO₄)₆Cl₂ 2 (Sr_(0.98),Eu_(0.01), Mn_(0.01))₁₀(PO₄)₆Cl₂ 3 (Sr_(0.97), Eu_(0.01),Mn_(0.02))₁₀(PO₄)₆Cl₂ 4 (Sr_(0.95), Eu_(0.01), Mn_(0.04))₁₀(PO₄)₆Cl₂ 5(Sr_(0.94), Eu_(0.01), Mn_(0.05))₁₀(PO₄)₆Cl₂ 6 (Sr_(0.95), Eu_(0.02),Mn_(0.03))₁₀(PO₄)₆Cl₂ 7 (Sr_(0.93), Eu_(0.05), Mn_(0.02))₁₀(PO₄)₆Cl₂ 8(Sr_(0.89), Eu_(0.10), Mn_(0.01))₁₀(PO₄)₆Cl₂ 9 (Ca_(0.96), Eu_(0.01),Mn_(0.03))₁₀(PO₄)₆Cl₂ 10 (Ca_(0.98), Eu_(0.01), Mn_(0.01))₁₀(PO₄)₆Cl₂ 11(Ca_(0.97), Eu_(0.01), Mn_(0.02))₁₀(PO₄)₆Cl₂ 12 (Ca_(0.95), Eu_(0.01),Mn_(0.04))₁₀(PO₄)₆Cl₂ 13 (Ca_(0.94), Eu_(0.01), Mn_(0.05))₁₀(PO₄)₆Cl₂ 14(Ca_(0.95), Eu_(0.02), Mn_(0.03))₁₀(PO₄)₆Cl₂ 15 (Ca_(0.93), Eu_(0.05),Mn_(0.02))₁₀(PO₄)₆Cl₂ 16 (Ca_(0.89), Eu_(0.10), Mn_(0.01))₁₀(PO₄)₆Cl₂ 17(Ba_(0.96), Eu_(0.01), Mn_(0.03))₁₀(PO₄)₆Cl₂

[0318] In Examples 2 to 8, the proportions of SrCO₃, MnCO₃ and Eu₂O₃ arechanged so that the fluorescent substances of compositions shown inTable 1 could be obtained.

[0319] In Examples 9 to 16, CaHPO₄, CaCO₃, Eu₂O₃, MnCO₃ and NH₄Cl wereused as the materials so that the fluorescent substances of compositionsshown in Table 1 could be obtained.

[0320] In Example 9, for example, the materials are weighed inproportions of CaHPO₄: 1000 g, CaCO₃: 441.4 g, Eu₂O₃: 21.6 g, MnCO₃:47.5 g and NH₄Cl: 157.3 g and well mixed in a mixer such as ball mill ina dry process. The mixed material is put into a crucible made of SiC,quartz or alumina and is fired in reducing atmosphere of N₂ or H₂ at1200° C. for 3 hours after raising the temperature to 1200° C. at a rateof 960° C./hr. The fired material is crushed in water, dispersed,sieved, separated, washed in water and dried thereby to obtain power ofthe desired fluorescent substance.

[0321] In Examples 10 to 16, fluorescent substances were prepared in thesame manner as in Example 9, except for changing the proportions ofCaCO₃ and MnCO₃.

[0322] In Example 17, BaHPO₄, BaCO₃, Eu₂O₃, MnCO₃ and NH₄Cl were used asthe materials so that the fluorescent substances of compositions shownin Table 1 could be obtained.

[0323] Specifically, the materials are weighed in proportions of BaHPO₄:1000 g, BaCO₃: 507.5 g, Eu₂O₃: 12.6 g, MnCO₃: 27.7 g and NH₄Cl: 91.7 gand well mixed in a mixer such as ball mill in a dry process. The mixedmaterial is put into a crucible made of SiC, quartz or alumina and isfired in reducing atmosphere of N₂ or H₂ at 1200° C. for 3 hours afterraising the temperature to 1200° C. at a rate of 960° C./hr. The firedmaterial is crushed in water, dispersed, sieved, separated, washed inwater and dried thereby to obtain power of the desired fluorescentsubstance. TABLE 2 Characteristics Chromaticity when Luminance whenLuminance when Examples excited at 365 nm excited at 400 nm excited at365 nm 1 (0.384, 0.332) approx. 237% approx. 157% 2 (0.309, 0.244)approx. 189% approx. 125% 3 (0.346, 0.287) approx. 201% approx. 133% 4(0.394, 0.337) approx. 212% approx. 142% 5 (0.405, 0.345) approx. 211%approx. 132% 6 (0.360, 0.317) approx. 248% approx. 157% 7 (0.398, 0.384)approx. 271% approx. 172% 8 (0.418, 0.400) approx. 263% approx. 165% 9(0.366, 0.280) approx. 266% approx. 182% 10 (0.183, 0.103) approx. 201%approx. 157% 11 (0.204, 0.125) approx. 219% approx. 162% 12 (0.344,0.252) approx. 233% approx. 175% 13 (0.372, 0.302) approx. 245% approx.171% 14 (0.354, 0.282) approx. 267% approx. 188% 15 (0.329, 0.261)approx. 311% approx. 201% 16 (0.309, 0.241) approx. 298% approx. 220% 17(0.184, 0.106) approx. 192% approx. 125%

[0324] Luminance when excited at 400 nm shown in Table 2 shows the ratioof luminance of emission when excited at 400 nm according to the Exampleto luminance of emission when excited at 400 nm according to theComparative Example, and luminance when excited at 400 nm shown in Table2 shows the ratio of luminance of emission when excited at 365 nmaccording to the Example to luminance of emission when excited at 365 nmaccording to the Comparative Example. The same applies to the table thatshows the characteristic of the other Examples.

[0325] In Examples 18 to 25, light emitting devices were produced in thesame manner as in Example 1, except for using the fluorescent substancesshown in Table 3 instead of the fluorescent substance of Example 1.

[0326] The results are shown Table 4. TABLE 3 Examples Fluorescentsubstances 18 (Sr_(0.70), Ba_(0.21), Ca_(0.05), Eu_(0.01),Mn_(0.03))₁₀(PO₄)₆Cl₂ 19 (Sr_(0.72), Ba_(0.21), Ca_(0.05), Eu_(0.01),Mn_(0.01))₁₀(PO₄)₆Cl₂ 20 (Sr_(0.71), Ba_(0.21), Ca_(0.05), Eu_(0.01),Mn_(0.02))₁₀(PO₄)₆Cl₂ 21 (Sr_(0.69), Ba_(0.21), Ca_(0.05), Eu_(0.01),Mn_(0.04))₁₀(PO₄)₆Cl₂ 22 (Sr_(0.68), Ba_(0.21), Ca_(0.05), Eu_(0.01),Mn_(0.05))₁₀(PO₄)₆Cl₂ 23 (Sr_(0.69), Ba_(0.21), Ca_(0.05), Eu_(0.02),Mn_(0.03))₁₀(PO₄)₆Cl₂ 24 (Sr_(0.67), Ba_(0.21), Ca_(0.05), Eu_(0.05),Mn_(0.02))₁₀(PO₄)₆Cl₂ 25 (Sr_(0.63), Ba_(0.21), Ca_(0.05), Eu_(0.10),Mn_(0.01))₁₀(PO₄)₆Cl₂

[0327] In Examples 18 to 25, the fluorescent substances of compositionsshown in Table 3 were prepared by using SrHPO₄, SrCO₃, CaCO₃, Eu₂O₃,MnCO₃ and NH₄Cl.

[0328] Specifically, in Example 8, the materials are weighed inproportions of SrHPO₄: 1000 g, SrCO₃: 134.0 g, BaCO₃: 376.2 g, CaCO₃:45.4 g, Eu₂O₃: 16.0 g, MnCO₃: 35.2 g and NH₄Cl: 116.5 g, and well mixedin a mixer such as ball mill in a dry process.

[0329] The mixed material is put into a crucible made of SiC, quartz oralumina and is fired in reducing atmosphere of N₂ or H₂ at 1200° C. for3 hours after raising the temperature to 1200° C. at a rate of 960°C./hr. The fired material is crushed in water, dispersed, sieved,separated, washed in water and dried thereby to obtain power of thedesired fluorescent substance.

[0330] Examples 19 to 25, fluorescent substances were prepared in thesame manner as in Example 18, except for changing the proportions ofSrCO₃ and MnCO₃. TABLE 4 Characteristics Chromaticity when Luminancewhen Luminance when Examples excited at 365 nm excited at 400 nm excitedat 365 nm 18 (0.374, 0.313) approx. 235% approx. 148% 19 (0.299, 0.222)approx. 182% approx. 121% 20 (0.326, 0.259) approx. 195% approx. 128% 21(0.374, 0.327) approx. 201% approx. 137% 22 (0.395, 0.332) approx. 205%approx. 130% 23 (0.348, 0.302) approx. 230% approx. 149% 24 (0.372,0.370) approx. 260% approx. 167% 25 (0.401, 0.392) approx. 243% approx.155%

[0331] In Examples 26 to 29, light emitting devices were produced in thesame manner as in Example 1, except for using the fluorescent substancesshown in Table 5 instead of the fluorescent substance of Example 1.

[0332] The results are shown Table 6. TABLE 5 Examples Fluorescentsubstances 26 (Sr_(0.70), Ba_(0.20), Ca_(0.05), Eu_(0.01), Mn_(0.03),Sn_(0.01))₁₀(PO₄)₆Cl₂ 27 (Sr_(0.70), Ba_(0.20), Ca_(0.05), Eu_(0.01),Mn_(0.03), Fe_(0.01))₁₀(PO₄)₆Cl₂ 28 (Sr_(0.70), Ba_(0.20), Ca_(0.05),Eu_(0.01), Mn_(0.03), Cr_(0.01))₁₀(PO₄)₆Cl₂ 29 (Sr_(0.65), Ba_(0.20),Ca_(0.05), Eu_(0.01), Mn_(0.03), Cr_(0.06))₁₀(PO₄)₆Cl₂

[0333] TABLE 6 Characteristics Chromaticity when Luminance whenLuminance when Examples excited at 365 nm excited at 400 nm excited at365 nm 26 (0.384, 0.294) approx. 230% approx. 138% 27 (0.392, 0.299)approx. 242% approx. 142% 28 (0.402, 0.278) approx. 222% approx. 132% 29(0.410, 0.269) approx. 198% approx. 125%

[0334] In Example 16, the materials of SrHPO₄, SrCO₃, BaCO₃, CaCO₃,Eu₂O₃, MnCO₃, NH₄Cl and SnO₂ are weighed in proportions corresponding tothe composition shown in Table 5 and well mixed in a mixer such as ballmill in a dry process. The mixed material is put into a crucible made ofSiC, quartz or alumina and is fired in reducing atmosphere of N₂ or H₂.The fired material is crushed in water, dispersed, sieved, separated,washed in water and dried thereby to obtain powder of the desiredfluorescent substance.

[0335] In Example 27, the materials of SrHPO₄, SrCO₃, BaCO₃, CaCO₃,Eu₂O₃, MnCO₃, NH₄Cl and Fe₂O₃ are weighed in proportions correspondingto the composition shown in Table 5, and the fluorescent substance isprepared in the same manner as in Example 26.

[0336] In Example 28, the materials of SrHPO₄, SrCO₃, BaCO₃, CaCO₃,Eu₂O₃, MnCO₃, NH₄Cl and Cr₂O₃ are weighed in proportions correspondingto the composition shown in Table 5, and the fluorescent substance isprepared in the same manner as in Example 26.

[0337] In Example 29, the materials of SrHPO₄, SrCO₃, BaCO₃, CaCO₃,Eu₂O₃, MnCO₃, NH₄Cl and Cr₂O₃ are weighed in proportions correspondingto the composition shown in Table 5, and the fluorescent substance isprepared in the same manner as in Example 26.

EXAMPLE 30

[0338] In Example 30, the light emitting device is produced in the samemanner as in Example 1, except for constituting the color conversionmember by using silicone that includes 50% by weight of the samefluorescent substance as that of Example 1.

[0339] The light emitting device of Example 30 can be mass-producedsatisfactorily, although the output power tends to decrease with timecompared to Example 1.

EXAMPLE 31

[0340] Example 31, light emitting device is produced in the same manneras in Example 1, except for forming the color conversion member byapplying silica gel that includes 50% by weight of the same fluorescentsubstance as that of Example 1.

[0341] The light emitting device of Example 31 has the same effect asthat of Example 1.

[0342] In Examples 32 to 43, light emitting devices were produced in thesame manner as in Example 1, except for using the fluorescent substancesshown in Table 7 were used instead of the fluorescent substance ofExample 1.

[0343] The results are shown in Table 8. TABLE 7 Examples Fluorescentsubstances 32 (Sr_(0.93), Eu_(0.05), Mn_(0.02))₁₀(PO₄)₆Br_(1.0)Cl_(1.0)33 (Sr_(0.93), Eu_(0.05), Mn_(0.02))₁₀(PO₄)₆Br₂ 34 (Sr_(0.93),Eu_(0.05), Mn_(0.02))₁₀(PO₄)₆Cl_(1.0)F_(1.0) 35 (Sr_(0.93), Eu_(0.05),Mn_(0.02))₁₀(PO₄)₆F₂ 36 (Sr_(0.93), Eu_(0.05),Mn_(0.02))₁₀(PO₄)₆Cl_(1.0)I_(1.0) 37 (Sr_(0.93), Eu_(0.05),Mn_(0.02))₁₀(PO₄)₆Cl_(1.0)F_(0.5)Br_(0.5) 38 (Sr_(0.93), Eu_(0.05),Mn_(0.02))₁₀(PO₄)₆Cl_(1.0)F_(0.5)I_(0.5) 39 (Sr_(0.93), Eu_(0.05),Mn_(0.02))₁₀(PO₄)₆Cl_(1.0)Br_(0.5)I_(0.5) 40 (Sr_(0.93), Eu_(0.05),Mn_(0.02))₁₀(PO₄)₆Cl_(0.5)F_(0.5)Br_(0.5)I_(0.5) 41 (Sr_(0.93),Eu_(0.05), Mn_(0.02))₁₀(PO₄)₆Cl_(0.5)F_(1.0)Br_(0.5) 42 (Sr_(0.93),Eu_(0.05), Mn_(0.02))₁₀(PO₄)₆Cl_(0.5)F_(1.0)I_(0.5) 43 (Sr_(0.93),Eu_(0.05), Mn_(0.02))₁₀(PO₄)₆Cl_(1.0)F_(0.4)I_(0.3)Br_(0.3)

[0344] The fluorescent substances of Examples 32 to 43 are prepared asdescribed below.

[0345] The fluorescent substance of Example 32 was prepared by replacinghalf of NH₄Cl among the materials used to prepare the fluorescentsubstance of Example 7 with NH₄Br.

[0346] The fluorescent substance of Example 33 was prepared by replacingall of NH₄Cl among the materials used to prepare the fluorescentsubstance of Example 7 with NH₄Br.

[0347] The fluorescent substance of Example 34 was prepared by replacinghalf of NH₄Cl among the materials used to prepare the fluorescentsubstance of Example 7 with NH₄F.

[0348] The fluorescent substance of Example 35 was prepared by replacingall of NH₄Cl among the materials used to prepare the fluorescentsubstance of Example 7 with NH₄F.

[0349] The fluorescent substance of Example 36 was prepared by replacinghalf of NH₄Cl among the materials used to prepare the fluorescentsubstance of Example 7 with NH₄I.

[0350] The fluorescent substance of Example 37 was prepared by replacinga part of NH₄Cl among the materials used to prepare the fluorescentsubstance of Example 7 with NH₄F and NH₄Br.

[0351] The fluorescent substance of Example 38 was prepared by replacinga part of NH₄Cl among the materials used to prepare the fluorescentsubstance of Example 7 with NH₄F and NH₄I.

[0352] The fluorescent substance of Example 39 was prepared by replacinga part of NH₄Cl among the materials used to prepare the fluorescentsubstance of Example 7 with NH₄Br and NH₄I.

[0353] The fluorescent substance of Example 40 was prepared by replacinga part of NH₄Cl among the materials used to prepare the fluorescentsubstance of Example 7 with NH₄F, NH₄Br and NH₄I.

[0354] The fluorescent substance of Example 41 was prepared by replacingNH₄Cl among the materials used to prepare the fluorescent substance ofExample 7 with NH₄F and NH₄Br.

[0355] The fluorescent substance of Example 42 was prepared by replacingNH₄Cl among the materials used to prepare the fluorescent substance ofExample 7 with NH₄F and NH₄I.

[0356] The fluorescent substance of Example 43 was prepared by replacingNH₄Cl among the materials used to prepare the fluorescent substance ofExample 7 with NH₄I and NH₄Br. TABLE 8 Characteristics Chromaticity whenLuminance when Luminance when Examples excited at 365 nm excited at 400nm excited at 365 nm 32 (0.358, 0.324) approx. 301% approx. 182% 33(0.348, 0.316) approx. 321% approx. 203% 34 (0.362, 0.352) approx. 290%approx. 166% 35 (0.348, 0.316) approx. 298% approx. 173% 36 (0.378,0.362) approx. 280% approx. 163% 37 (0.363, 0.337) approx. 293% approx.175% 38 (0.368, 0.347) approx. 263% approx. 158% 39 (0.361, 0.337)approx. 293% approx. 178% 40 (0.358, 0.332) approx. 295% approx. 178% 41(0.348, 0.322) approx. 315% approx. 198% 42 (0.373, 0.342) approx. 275%approx. 168% 43 (0.372, 0.342) approx. 283% approx. 168%

[0357] In Examples 44 to 55, light emitting devices were produced in thesame manner as in Example 1, except for using the fluorescent substancesshown in Table 9 instead of the fluorescent substance of Example 1.

[0358] The results are shown Table 10. TABLE 9 Examples Fluorescentsubstances 44 (Ca_(0.93), Eu_(0.05), Mn_(0.02))₁₀(PO₄)₆Br_(1.0)Cl_(1.0)45 (Ca_(0.93), Eu_(0.05), Mn_(0.02))₁₀(PO₄)₆Br₂ 46 (Ca_(0.93),Eu_(0.05), Mn_(0.02))₁₀(PO₄)₆Cl_(1.0)F_(1.0) 47 (Ca_(0.93), Eu_(0.05),Mn_(0.02))₁₀(PO₄)₆F₂ 48 (Ca_(0.93), Eu_(0.05),Mn_(0.02))₁₀(PO₄)₆Cl_(1.0)I_(1.0) 49 (Ca_(0.93), Eu_(0.05),Mn_(0.02))₁₀(PO₄)₆Cl_(1.0)F_(0.5)Br_(0.5) 50 (Ca_(0.93), Eu_(0.05),Mn_(0.02))₁₀(PO₄)₆Cl_(1.0)F_(0.5)I_(0.5) 51 (Ca_(0.93), Eu_(0.05),Mn_(0.02))₁₀(PO₄)₆Cl_(1.0)Br_(0.5)I_(0.5) 52 (Ca_(0.93), Eu_(0.05),Mn_(0.02))₁₀(PO₄)₆Cl_(0.5)F_(0.5)Br_(0.5)I_(0.5) 53 (Ca_(0.93),Eu_(0.05), Mn_(0.02))₁₀(PO₄)₆F_(1.0)Br_(1.0) 54 (Ca_(0.93), Eu_(0.05),Mn_(0.02))₁₀(PO₄)₆F_(1.0)I_(1.0) 55 (Sr_(0.93), Eu_(0.05),Mn_(0.02))₁₀(PO₄)₆I_(1.0)Br_(1.0)

[0359] The fluorescent substances of Examples 44 to 55 are prepared asdescribed below.

[0360] The fluorescent substance of Example 44 was prepared by replacingall of NH₄Cl among the materials used to prepare the fluorescentsubstance of Example 15 with NH₄Br.

[0361] The fluorescent substance of Example 46 was prepared by replacinghalf of NH₄Cl among the materials used to prepare the fluorescentsubstance of Example 15 with NH₄F.

[0362] The fluorescent substance of Example 47 was prepared by replacingall of NH₄Cl among the materials used to prepare the fluorescentsubstance of Example 15 with NH₄F.

[0363] The fluorescent substance of Example 48 was prepared by replacinghalf of NH₄Cl among the materials used to prepare the fluorescentsubstance of Example 15 with NH₄I.

[0364] The fluorescent substance of Example 49 was prepared by replacinga part of NH₄Cl among the materials used to prepare the fluorescentsubstance of Example 15 with NH₄F and NH₄Br.

[0365] The fluorescent substance of Example 50 was prepared by replacinga part of NH₄Cl among the materials used to prepare the fluorescentsubstance of Example 15 with NH₄F and NH₄I.

[0366] The fluorescent substance of Example 51 was prepared by replacinga part of NH₄Cl among the materials used to prepare the fluorescentsubstance of Example 15 with NH₄Br and NH₄I.

[0367] The fluorescent substance of Example 52 was prepared by replacinga part of NH₄Cl among the materials used to prepare the fluorescentsubstance of Example 15 with NH₄F, NH₄Br and NH₄I.

[0368] The fluorescent substance of Example 53 was prepared by replacingNH₄Cl among the materials used to prepare the fluorescent substance ofExample 15 with NH₄F and NH₄Br.

[0369] The fluorescent substance of Example 54 was prepared by replacingNH₄Cl among the materials used to prepare the fluorescent substance ofExample 15 with NH₄F and NH₄I.

[0370] The fluorescent substance of Example 55 was prepared by replacingNH₄Cl among the materials used to prepare the fluorescent substance ofExample 15 with NH₄I and NH₄Br. TABLE 10 Characteristics Chromaticitywhen Luminance when Luminance when Examples excited at 365 nm excited at400 nm excited at 365 nm 44 (0.350, 0.328) approx. 341% approx. 222% 45(0.340, 0.324) approx. 361% approx. 243% 46 (0.354, 0.348) approx. 330%approx. 196% 47 (0.356, 0.320) approx. 338% approx. 203% 48 (0.370,0.358) approx. 320% approx. 207% 49 (0.355, 0.333) approx. 323% approx.205% 50 (0.362, 0.343) approx. 303% approx. 188% 51 (0.353, 0.341)approx. 331% approx. 208% 52 (0.364, 0.336) approx. 339% approx. 214% 53(0.356, 0.326) approx. 345% approx. 228% 54 (0.362, 0.338) approx. 315%approx. 198% 55 (0.363, 0.351) approx. 318% approx. 195%

[0371] In Examples 56 to 67, light emitting devices were produced in thesame manner as in Example 1, except for using the fluorescent substancesshown in Table 11 instead of the fluorescent substance of Example 1.

[0372] The results are shown Table 12. TABLE 11 Examples Fluorescentsubstances 56 (Sr_(0.67), Ba_(0.21), Ca_(0.05),Mn_(0.02))₁₀(PO₄)₆Br_(1.0)Cl_(1.0) 57 (Sr_(0.67), Ba_(0.21), Ca_(0.05),Mn_(0.02))₁₀(PO₄)₆Br₂ 58 (Sr_(0.67), Ba_(0.21), Ca_(0.05),Mn_(0.02))₁₀(PO₄)₆Cl_(1.0)F_(1.0) 59 (Sr_(0.67), Ba_(0.21), Ca_(0.05),Mn_(0.02))₁₀(PO₄)₆F_(2.0) 60 (Sr_(0.67), Ba_(0.21), Ca_(0.05),Mn_(0.02))₁₀(PO₄)₆Cl_(1.0)I_(1.0) 61 (Sr_(0.67), Ba_(0.21), Ca_(0.05),Mn_(0.02))₁₀(PO₄)₆Cl_(1.0)F_(0.5)Br_(0.5) 62 (Sr_(0.67), Ba_(0.21),Ca_(0.05), Mn_(0.02))₁₀(PO₄)₆Cl_(1.0)F_(0.5)I_(0.5) 63 (Sr_(0.67),Ba_(0.21), Ca_(0.05), Mn_(0.02))₁₀(PO₄)₆Cl_(1.0)Br_(0.5)I_(0.5) 64(Sr_(0.67), Ba_(0.21), Ca_(0.05),Mn_(0.02))₁₀(PO₄)₆Cl_(0.5)F_(0.5)Br_(0.5)I_(0.5) 65 (Sr_(0.67),Ba_(0.21), Ca_(0.05), Mn_(0.02))₁₀(PO₄)₆F_(1.0)Br_(1.0) 66 (Sr_(0.67),Ba_(0.21), Ca_(0.05), Mn_(0.02))₁₀(PO₄)₆F_(1.0)I_(1.0) 67 (Sr_(0.67),Ba_(0.21), Ca_(0.05), Mn_(0.02))₁₀(PO₄)₆I_(1.0)Br_(1.0)

[0373] The fluorescent substances of Examples 56 to 67 are prepared asdescribed below.

[0374] The fluorescent substance of Example 56 was prepared by replacinghalf of NH₄Cl among the materials used to prepare the fluorescentsubstance of Example 24 with NH₄Br.

[0375] The fluorescent substance of Example 57 was prepared by replacingall of NH₄Cl among the materials used to prepare the fluorescentsubstance of Example 24 with NH₄Br.

[0376] The fluorescent substance of Example 58 was prepared by replacinghalf of NH₄Cl among the materials used to prepare the fluorescentsubstance of Example 24 with NH₄F.

[0377] The fluorescent substance of Example 59 was prepared by replacingall of NH₄Cl among the materials used to prepare the fluorescentsubstance of Example 24 with NH₄F.

[0378] The fluorescent substance of Example 60 was prepared by replacinghalf of NH₄Cl among the materials used to prepare the fluorescentsubstance of Example 24 with NH₄I.

[0379] The fluorescent substance of Example 61 was prepared by replacinga part of NH₄Cl among the materials used to prepare the fluorescentsubstance of Example 24 with NH₄F and NH₄Br.

[0380] The fluorescent substance of Example 62 was prepared by replacinga part of NH₄Cl among the materials used to prepare the fluorescentsubstance of Example 24 with NH₄F and NH₄I.

[0381] The fluorescent substance of Example 63 was prepared by replacinga part of NH₄Cl among the materials used to prepare the fluorescentsubstance of Example 24 with NH₄Br and NH₄I.

[0382] The fluorescent substance of Example 64 was prepared by replacinga part of NH₄Cl among the materials used to prepare the fluorescentsubstance of Example 24 with NH₄F, NH₄Br and NH₄I.

[0383] The fluorescent substance of Example 65 was prepared by replacingNH₄Cl among the materials used to prepare the fluorescent substance ofExample 24 with NH₄F and NH₄Br.

[0384] The fluorescent substance of Example 66 was prepared by replacingNH₄Cl among the materials used to prepare the fluorescent substance ofExample 24 with NH₄F and NH₄I.

[0385] The fluorescent substance of Example 67 was prepared by replacingNH₄Cl among the materials used to prepare the fluorescent substance ofExample 24 with NH₄I and NH₄Br. TABLE 12 Characteristics Chromaticitywhen Luminance when Luminance when Examples excited at 365 nm excited at400 nm excited at 365 nm 56 (0.354, 0.322) approx. 311% approx. 188% 57(0.344, 0.314) approx. 331% approx. 209% 58 (0.358, 0.350) approx. 300%approx. 172% 59 (0.344, 0.314) approx. 308% approx. 179% 60 (0.374,0.360) approx. 290% approx. 169% 61 (0.359, 0.335) approx. 303% approx.181% 62 (0.364, 0.345) approx. 273% approx. 164% 63 (0.357, 0.335)approx. 305% approx. 164% 64 (0.354, 0.330) approx. 305% approx. 184% 65(0.344, 0.320) approx. 325% approx. 204% 66 (0.369, 0.340) approx. 285%approx. 172% 67 (0.368, 0.340) approx. 293% approx. 174%

[0386] In Examples 68 to 77, light emitting devices were produced asdescribed below with the results shown Table 13.

EXAMPLE 68

[0387] In Example 68, the light emitting device is produced in the samemanner, except for adding SrAl₂O₄:Eu fluorescent substance that emitsgreen light as the second fluorescent substance to(Sr_(0.93),Eu_(0.5))₁₀(PO₄)₆Cl₂ fluorescent substance of Example 9.

EXAMPLE 69

[0388] In Example 69, the light emitting device is produced in the samemanner, except for adding (Sr_(0.93),Eu_(0.5))₁₀(PO₄)₆Cl₂ fluorescentsubstance that emits blue light as the third fluorescent substance tothe two kinds of fluorescent substance of Example 9.

EXAMPLE 70

[0389] In Example 70, the light emitting device is produced in the samemanner, except for adding La₂O₂S:Eu fluorescent substance that emits redlight as the fourth fluorescent substance to the three kinds offluorescent substance of Example 69.

EXAMPLE 71

[0390] In Example 71, the light emitting device is produced in the samemanner, except for adding (Sr_(0.93),Eu_(0.5))₁₀(PO₄)₆Cl₂ fluorescentsubstance that emits blue light as the third fluorescent substance tothe two kinds of fluorescent substance of the Example 69.

EXAMPLE 72

[0391] In Example 71, the light emitting device is produced in the samemanner, except for adding La₂O₂S:Eu fluorescent substance that emits redlight as the fourth fluorescent substance to the three kinds offluorescent substance of Example 69.

EXAMPLE 73

[0392] In Example 73, the light emitting device is produced in the samemanner, except for adding a fluorescent substance prepared by mixing thematerials of CaHPO₄, CaCO₃, Eu₂O₃, MnCO₃ and NH₄Cl in proportionscorresponding to the composition of (Ca_(0.88), Eu_(1.0),Mn_(0.02))₁₀(PO₄)₆Cl₂, and Sr₄Al₁₄O₂₅:Eu fluorescent substance thatemits blue green light as the second fluorescent substance to the threekinds of fluorescent substance of Example 69.

EXAMPLE 74

[0393] In Example 74, the light emitting device is produced in the samemanner, except for adding (Ca_(0.93),Eu_(0.5))₁₀(PO₄)₆Cl₂ fluorescentsubstance as the third fluorescent substance to the two kinds offluorescent substance of Example 71.

EXAMPLE 73

[0394] In Example 75, the light emitting device is produced in the samemanner, except for adding La₂O₂S:Eu fluorescent substance that emits redlight as the fourth fluorescent substance to the three kinds offluorescent substance of Example 74.

EXAMPLE 76

[0395] In Example 76, the light emitting device is produced in the samemanner, except for adding (Ca_(0.93),Eu_(0.5))₁₀(PO₄)₆Cl₂ fluorescentsubstance as the third fluorescent substance to the two kinds offluorescent substance of Example 73.

EXAMPLE 77

[0396] In Example 77, the light emitting device is produced in the samemanner, except for adding La₂O₂S:Eu fluorescent substance that emits redlight as the fourth fluorescent substance to the three kinds offluorescent substance of Example 71. TABLE 13 CharacteristicsChromaticity when Luminance when Luminance when Examples excited at 365nm excited at 400 nm excited at 365 nm 68 (0.357, 0.378) approx. 360%approx. 235% 69 (0.312, 0.322) approx. 320% approx. 173% 70 (0.353,0.321) approx. 310% approx. 168% 71 (0.313, 0.325) approx. 315% approx.170% 72 (0.356, 0.319) approx. 305% approx. 166% 73 (0.353, 0.349)approx. 375% approx. 245% 74 (0.315, 0.325) approx. 325% approx. 169% 75(0.353, 0.324) approx. 317% approx. 175% 76 (0.315, 0.327) approx. 317%approx. 172% 77 (0.354, 0.321) approx. 312% approx. 171%

[0397] In Examples 78 to 154, light emitting devices were produced inthe same manner as in Example 1, except for using the first fluorescentsubstance and the second fluorescent substance shown in Table 14 as thefluorescent substance. In Examples 78 to 154, the composition of thelight emitting layer of the LED chip was adjusted so as to emit light ofwavelength 400 nm.

[0398] In the column of first fluorescent substance in Table 14, entryof “Example 1” means that the same fluorescent substance as that ofExample 1 is used.

[0399] As shown in Table 14, the light emitting devices of the Examples78 to 154 are prepared by using the same fluorescent substances as thoseof Examples 1 to 77 are used as the first fluorescent substance, andusing Y₃Al₅O₁₂:Ce(YAG:Ce) as the second fluorescent substance.

[0400] The second fluorescent substance is prepared by putting a mixtureof oxides Y₂O₂, Gd₂O₃ and CeO₂ and flux such as fluoride in a crucibleand firing the mixture in reducing atmosphere at 1400° C. for 3 to 7hours, with the fired material being ball-milled, washed, separated,dried and sieved.

[0401] The second fluorescent substance may also be prepared in the samemanner as in the method described above, except for using acoprecipitated oxide obtained by coprecipitation, with oxalic acid, asolution that is prepared by dissolving a rare earth element such as Y,Gs or Ce in stoichiometrical proportion in an acid, and firing thecoprecipitate and aluminum oxide are mixed, with the mixture and bariumfluoride used as flux being mixed and put into a crucible.

[0402] In Examples 78 to 154, a paste that has been prepared by addingthe first fluorescent substance prepared in the same manner as inExamples 1 to 77, the second fluorescent substance prepared as describedabove and filler or diffusing agent made of SiO₂ to a slurry including90% by weight of nitrocellulose, 10% by weight of γ-alumina, is appliedto the back surface of the light transmitting window of the lid, and ishardened by heating at 220° C. for 30 minutes so as to form a colorconversion member.

[0403] After completely purging moisture from the recess of the package,the light emitting device is completed by sealing the recess with thelid made of Kovar that has a glass window at the center thereof andapplying seam welding.

[0404] The light emitting device of Example 78 that has been produced asdescribed above emits white light showing chromaticity coordinates (x,y)=(0.360, 0.370) as shown in Table 14, and shows luminance of 24 lm/Wwhen driven with a current of 20 mA.

[0405] Table 14 shows the characteristics (chromaticity coordinates andluminance when driven with 20 mA) of the light emitting devices ofExamples 78 to 154. TABLE 14 First Second Luminance fluorescentfluorescent Chromaticity of emission Examples substance substance (x, y)lm/W  78 Example 1 Y₃Al₅O₁₂:Ce 0.360, 0.370 24  79 Example 2 Y₃Al₅O₁₂:Ce0.275, 0.280 16  80 Example 3 Y₃Al₅O₁₂:Ce 0.325, 0.332 18  81 Example 4Y₃Al₅O₁₂:Ce 0.367, 0.386 25  82 Example 5 Y₃Al₅O₁₂:Ce 0.370, 0.401 26 83 Example 6 Y₃Al₅O₁₂:Ce 0.363, 0.375 24  84 Example 7 Y₃Al₅O₁₂:Ce0.355, 0.362 23  85 Example 8 Y₃Al₅O₁₂:Ce 0.349, 0.354 21  86 Example 9Y₃Al₅O₁₂:Ce 0.362, 0.372 29  87 Example 10 Y₃Al₅O₁₂:Ce 0.277, 0.283 21 88 Example 11 Y₃Al₅O₁₂:Ce 0.327, 0.335 23  89 Example 12 Y₃Al₅O₁₂:Ce0.365, 0.382 30  90 Example 13 Y₃Al₅O₁₂:Ce 0.370, 0.398 31  91 Example14 Y₃Al₅O₁₂:Ce 0.361, 0.376 29  92 Example 15 Y₃Al₅O₁₂:Ce 0.358, 0.35728  93 Example 16 Y₃Al₅O₁₂:Ce 0.351, 0.353 26  94 Example 17 Y₃Al₅O₁₂:Ce0.263, 0.260 15  95 Example 18 Y₃Al₅O₁₂:Ce 0.356, 0.368 25  96 Example19 Y₃Al₅O₁₂:Ce 0.278, 0.282 17  97 Example 20 Y₃Al₅O₁₂:Ce 0.326, 0.33420  98 Example 21 Y₃Al₅O₁₂:Ce 0.362, 0.381 31  99 Example 22 Y₃Al₅O₁₂:Ce0.369, 0.395 31 100 Example 23 Y₃Al₅O₁₂:Ce 0.357, 0.371 29 101 Example24 Y₃Al₅O₁₂:Ce 0.357, 0.362 28 102 Example 25 Y₃Al₅O₁₂:Ce 0.349, 0.35625 103 Example 26 Y₃Al₅O₁₂:Ce 0.370, 0.381 27 104 Example 27 Y₃Al₅O₁₂:Ce0.372, 0.383 27 105 Example 28 Y₃Al₅O₁₂:Ce 0.375, 0.386 28 106 Example29 Y₃Al₅O₁₂:Ce 0.389, 0.402 29 107 Example 1 Y₃Al₅O₁₂:Ce Similar toExample 78 108 Example 1 Y₃Al₅O₁₂:Ce Similar to Example 78 109 Example32 Y₃Al₅O₁₂:Ce 0.357, 0.361 28 110 Example 33 Y₃Al₅O₁₂:Ce 0.357, 0.36328 111 Example 34 Y₃Al₅O₁₂:Ce 0.349, 0.357 24 112 Example 35 Y₃Al₅O₁₂:Ce0.347, 0.353 23 113 Example 36 Y₃Al₅O₁₂:Ce 0.356, 0.361 22 114 Example37 Y₃Al₅O₁₂:Ce 0.351, 0.361 25 115 Example 38 Y₃Al₅O₁₂:Ce 0.357, 0.36723 116 Example 39 Y₃Al₅O₁₂:Ce 0.357, 0.366 25 117 Example 40 Y₃Al₅O₁₂:Ce0.348, 0.356 24 118 Example 41 Y₃Al₅O₁₂:Ce 0.348, 0.356 25 119 Example42 Y₃Al₅O₁₂:Ce 0.351, 0.358 22 120 Example 43 Y₃Al₅O₁₂:Ce 0.349, 0.35824 121 Example 44 Y₃Al₅O₁₂:Ce 0.353, 0.363 31 122 Example 45 Y₃Al₅O₁₂:Ce0.355, 0.361 33 123 Example 46 Y₃Al₅O₁₂:Ce 0.348, 0.357 29 124 Example47 Y₃Al₅O₁₂:Ce 0.346, 0.352 28 125 Example 48 Y₃Al₅O₁₂:Ce 0.355, 0.36227 126 Example 49 Y₃Al₅O₁₂:Ce 0.352, 0.363 30 127 Example 50 Y₃Al₅O₁₂:Ce0.357, 0.364 28 128 Example 51 Y₃Al₅O₁₂:Ce 0.355, 0.364 30 129 Example52 Y₃Al₅O₁₂:Ce 0.349, 0.357 29 130 Example 53 Y₃Al₅O₁₂:Ce 0.347, 0.35830 131 Example 54 Y₃Al₅O₁₂:Ce 0.349, 0.359 27 132 Example 55 Y₃Al₅O₁₂:Ce0.348, 0.356 29 133 Example 56 Y₃Al₅O₁₂:Ce 0.355, 0.362 29 134 Example57 Y₃Al₅O₁₂:Ce 0.350, 0.357 30 135 Example 58 Y₃Al₅O₁₂:Ce 0.349, 0.35827 136 Example 59 Y₃Al₅O₁₂:Ce 0.357, 0.363 26 137 Example 60 Y₃Al₅O₁₂:Ce0.357, 0.366 24 138 Example 61 Y₃Al₅O₁₂:Ce 0.353, 0.360 29 139 Example62 Y₃Al₅O₁₂:Ce 0.350, 0.361 27 140 Example 63 Y₃Al₅O₁₂:Ce 0.349, 0.35624 141 Example 64 Y₃Al₅O₁₂:Ce 0.351, 0.362 28 142 Example 65 Y₃Al₅O₁₂:Ce0.348, 0.353 29 143 Example 66 Y₃Al₅O₁₂:Ce 0.362, 0.370 25 144 Example67 Y₃Al₅O₁₂:Ce 0.350, 0.358 28 145 Example 68 Y₃Al₅O₁₂:Ce 0.357, 0.36332 146 Example 69 Y₃Al₅O₁₂:Ce 0.323, 0.332 27 147 Example 70 Y₃Al₅O₁₂:Ce0.367, 0.373 31 148 Example 71 Y₃Al₅O₁₂:Ce 0.357, 0.363 25 149 Example72 Y₃Al₅O₁₂:Ce 0.367, 0.370 29 150 Example 73 Y₃Al₅O₁₂:Ce 0.353, 0.36231 151 Example 74 Y₃Al₅O₁₂:Ce 0.333, 0.345 27 152 Example 75 Y₃Al₅O₁₂:Ce0.362, 0.370 29 153 Example 76 Y₃Al₅O₁₂:Ce 0.337, 0.348 26 154 Example77 Y₃Al₅O₁₂:Ce 0.362, 0.368 28

[0406] The light emitting device of Example 107 was produced in the samemanner as in Example 31, except for forming the color conversion memberin the same manner as in Example 30 and the light emitting device ofExample 108 was produced in the same manner as in Example 78, except forforming the color conversion member in the same manner as in Example 31.

[0407] While chromaticity when excited with 365 nm is shown for Examples1 to 154, similar values of chromaticity were observed in both cases ofexciting with 400 nm and 365 nm in Examples 1 to 154.

[0408] As described above byway of Example, the present inventionprovides the light emitting device that has good color renderingperformance and can suppress changes in chromaticity.

[0409] Also according to the present invention, desired color tone canbe achieved by controlling the composition of the fluorescent substance,when the fluorescent substance is excited by light in a region rangingfrom ultraviolet to visible light of short wavelengths.

INDUSTRIAL APPLICABILITY

[0410] The light emitting device of the present invention makes use ofthe advantages of the semiconductor light emitting element and providesbetter light source than the prior art for applications includingillumination.

[0411] Thus, the present invention provides the excellent light emittingdevice that can be used for such applications as signal light,illumination, display, indicator and other light sources.

1. A first light emitting device comprising: a light emitting elementand a fluorescent substance that is excited by the light emittingelement, wherein the light emitting element has an emission spectrum ina region from ultraviolet to visible light of short wavelengths, and thefluorescent substance has an emission spectrum that includes two or moreemission peaks with at least two peaks of the two or more peaks being inthe relation of complementary colors of each other.
 2. The lightemitting device according to claim 1: wherein a main emission wavelengthof said light emitting element longer than 360 nm in the ultravioletregion.
 3. The light emitting device according to claims 1 or 2: whereinthe emission peak of shorter wavelength of the two emission peaks whichare in the relation of complementary colors of each other has smallerhalf width than the other emission peak.
 4. The light emitting device asin any one of claims 1-3 further comprising: an additional fluorescentsubstance that has another emission peak between said two emission peaksthat are complementary colors of each other.
 5. The light emittingdevice as in any one of claims 1-4: wherein a luminous color is set bycontrolling the composition of the fluorescent substance to adjust theintensity ratio of the two emission peaks that are complementary colorsof each other.
 6. A light emitting device comprising: a light emittingelement and a fluorescent substance that is excited by said lightemitting element, wherein said light emitting element has an emissionspectrum in a region from ultraviolet to visible light of shortwavelengths, and the fluorescent substance is Eu-activated alkali earthmetal halogen-apatite fluorescent substance that includes at least anelement selected from the group consisting of Mg, Ca, Ba, Sr and Zn andan element selected from the group consisting of Mn, Fe, Cr and Sn. 7.The light emitting device according to claim 1 or 6, wherein said lightemitting element has an active layer consist of a nitride semiconductorincluding at least In and Ga.
 8. The light emitting device according toclaim 1 or 6, wherein said light emitting element has an active layerconsist of a nitride semiconductor including at least Ga and Al.
 9. Thelight emitting device as in one of claims 1, 6-8: wherein said lightemitting element has an n-type nitride semiconductor layer including ann-type contact layer, an active layer and a p-type nitride semiconductorlayer including a p-type contact layer, said p-type contact layer havinga light transmitting p-electrode of metal selected from the groupconsisting of gold and platinum group, said light transmittingp-electrode covering substantially the entire surface of said p-typecontact layer, wherein a thickness of said light transmittingp-electrode and a thickness of the n-type contact layer being set sothat sheet resistance Rp Ω/□ of said light transmitting p-electrode andsheet resistance Rn Ω/□ of said n-type contact layer satisfy therelationship of Rp≧Rn.
 10. The light emitting device according to claim9: wherein the sheet resistance of said light transmitting p-electrodeis 10 Ω/□ or higher.
 11. The light emitting device according to claims 9or 10: wherein the thickness of said light transmitting p-electrode isnot more than 150 Å.
 12. The light emitting device as in one of claims9-11: further comprising an n-electrode disposed in the vicinity of atleast one side of said semiconductor light emitting element on saidn-type contact layer and a base electrode formed at a position adjacentto the side that opposes the side in the vicinity of which then-electrode is disposed on the light transmitting p electrode, whereinextension conductors are connected to said base electrode, saidextension conductors extending along the side of the light transmittingp-electrode on both sides thereof in the vicinity of which the baseelectrodes are located.
 13. The light emitting device according to claim12: wherein said n-electrode is disposed at one corner of saidsemiconductor light emitting element so as to be close to two sidesthereof, and said base electrode is located at the other corner oppositeto said one corner.
 14. The light emitting device according to claims 12or 13: wherein said extension conductors are formed in an arc shape soas to be equi-distanced from the n electrode.
 15. The light emittingdevice as in one of claims 6-14: wherein said fluorescent substance isEu-activated alkali earth metal halogen-apatite fluorescent substanceincluding at least Mn and/or Cl.
 16. The light emitting device as in oneof claims 6-14: wherein said fluorescent substance is represented by(M_(1-x-y)Eu_(x)M′_(y))₁₀(PO₄)₆Q₂ (M represents at least one kind ofelement selected from Mg, Ca, Ba, Sr and Zn, M′ represents at least onekind of element selected from Mn, Fe, Cr and Sn, and Q represents atleast one kind of halogen element selected from F, Cl, Br and I, where0.0001≦x≦0.5 and 0.0001≦y≦0.5).
 17. The light emitting device accordingto claim 16: wherein Cl is used for Q in said formula.
 18. The lightemitting device as in one of claims 1-17: further comprising afluorescent substance selected from the group consisting ofBaMg₂Al₁₆O₂₇:Eu, BaMgAl₁₀O₁₇:Eu, BaMgAl₁₀O₁₇:Eu,Mn,(Sr,Ca,Ba)₅(PO₄)₃Cl:Eu, (Sr,Ca,Ba)₁₀(PO₄)₆Cl₂, SrAl₂O₄:Eu,Sr₄Al₁₄O₂₅:Eu, ZnS:Cu, Zn₂GeO₄:Mn, BaMg₂Al₁₆O₂₇:Eu,Mn, Y₂O₂S:Eu,La₂O₂S:Eu and Gd₂O₂S:Eu.
 19. The light emitting device as in one ofclaims 16-18: further comprising a fluorescent substance represented by(M_(1-x)Eu_(x))₁₀(PO₄)₆Q₂ in which M represents at least one kind ofelement selected from Mg, Ca, Ba, Sr and Zn, and Q represents at leastone kind of halogen element selected from F, Cl, Br and I, where0.0001≦x≦0.5 and 0.0001≦y≦0.5.
 20. The light emitting device accordingto claim 19: wherein Cl is used for Q in said formula.
 21. A lightemitting device comprising: a light emitting element and a fluorescentsubstance that is excited by the light emitting element, wherein saidlight emitting element has an emission spectrum in from ultraviolet tovisible light of short wavelengths, and said fluorescent substance isalkali earth metal halogen-apatite fluorescent substance that includesat least an element selected from Mg, Ca, Ba, Sr and Zn and an elementselected from Mn, Fe, Cr and Sn.
 22. The light emitting device accordingto claim 21: wherein said fluorescent substance is alkali earth metalhalogen-apatite fluorescent substance including at least Mn and/or Cl.23. A light emitting device comprising: a light emitting element and afluorescent substance that is excited by the light emitting element,wherein said light emitting element has an emission spectrum in a regionranging from ultraviolet to visible light of short wavelengths, and saidfluorescent substance includes a first fluorescent substance that has anemission spectrum different from that of the light emitting element anda second fluorescent substance that has an emission spectrum differentfrom that of said first fluorescent substance.
 24. The light emittingdevice according to claim 23: wherein said second fluorescent substanceis excited at least one of the light emitted by said light emittingelement and light emitted by said first fluorescent substance.
 25. Thelight emitting device according to claims 23 or 24: wherein the emissionspectrum of at least one of said first fluorescent substance and saidsecond fluorescent substance has two or more peaks, of which two are inthe relationship of complementary colors of each other.
 26. The lightemitting device as in one of claims 23-25: wherein the peak wavelengthof said light emitting element is in the relationship of complementarycolors with any one of the peaks of said first fluorescent substance andsaid second fluorescent substance.
 27. The light emitting device as inone of claims 23-25: wherein said first fluorescent substance has anemission spectrum having a peak wavelength that is in the relationshipof complementary colors with the peak wavelength of the emissionspectrum of the second fluorescent substance.
 28. The light emittingdevice as in one of claims 23-27: wherein the main emission wavelengthof said light emitting element is longer than 360 nm in the ultravioletregion.
 29. The light emitting device as in one of claims 23-28: whereinsaid second fluorescent substance is a cerium-activated fluorescentsubstance based on yttrium aluminum oxide.
 30. The light emitting deviceas in one of claims 23-29: wherein said first fluorescent substance is aEu-activated alkali earth metal halogen-apatite fluorescent substanceincluding at least an element selected from Mg, Ca, Ba, Sr and Zn and anelement selected from Mn, Fe, Cr and Sn.
 31. The light emitting deviceas in one of claims 23-30: wherein said first fluorescent substance is afluorescent substance selected from the group consisting of, (1) Afluorescent substance represented by (M1_(1-a-b)Eu_(a)L1_(b))₁₀(PO₄)₆Q₂in which M1 represents at least one element selected from Mg, Ca, Ba, Srand Zn, L1 represents at least one element selected from Mn, Fe, Cr andSn, and Q represents at least one halogen element selected from F, Cl,Br and I, where 0.0001≦a≦0.5 and 0.0001≦b≦0.5; (2) A fluorescentsubstance represented by (M1_(1-a)Eu_(a))₁₀(PO₄)₆Q₂ in which M1represents at least one element selected from Mg, Ca, Ba, Sr and Zn, andQ represents at least one halogen element selected from F, Cl, Br and I,where 0.0001≦a≦0.5; (3) A fluorescent substance represented by(M1_(1-a-b)Eu_(a)Mn_(b))₁₀(PO₄)₆Q₂ in which M1 represents at least oneelement selected from Mg, Ca, Ba, Sr and Zn, and Q represents at leastone halogen element selected from F, Cl, Br and I, where 0.0001≦a≦0.5and 0.0001≦b≦0.5; (4) A fluorescent substance represented by(M2_(1-a-c)Eu_(a)Ba_(c))₁₀(PO₄)₆Q₂ in which M2 represents at least oneelement selected from Mg, Ca, Sr and Zn, and Q represents at least onehalogen element selected from F, Cl, Br and I, where 0.0001≦a≦0.5 and0.10≦c≦0.98; (5) A fluorescent substance represented byM1_(1-a)Eu_(a)Al₂O₄ in which M1 represents at least one element selectedfrom Mg, Ca, Ba, Sr and Zn, where 0.0001≦a≦0.5; (6) A fluorescentsubstance represented by M1_(1-a-b)Eu_(a)Mn_(b)Al₂O₄ in which M1represents at least one element selected from Mg, Ca, Ba, Sr and Zn,where 0.0001≦a≦0.5 and 0.0001≦b≦0.5; (7) A fluorescent substancerepresented by M3_(1-a-c)Eu_(a)Ca_(c)Al₂O₄ in which M3 represents atleast one element selected from Mg, Ba, Sr and Zn, where 0.0001≦a≦0.5and 0.10≦c≦0.98; (8) A fluorescent substance represented byM4_(1-a)Eu_(a)MgAl₁₀O₁₇ in which M4 represents at least one elementselected from Ca, Ba, Sr and Zn, where 0.0001≦a≦0.5; (9) A fluorescentsubstance represented by M4_(1-a)Eu_(a)Mg_(1-b)Mn_(b)Al₁₀O₁₇ in which M4represents at least one element selected from Ca, Ba, Sr and Zn where0.0001≦a≦0.5 and 0.0001≦b≦0.5; (10) A fluorescent substance representedby (M1_(1-a)Eu_(a))₄Al₁₄O₂₅ in which M1 represents at least one elementselected from Mg, Ca, Ba, Sr and Zn, where 0.0001≦a≦0.5; (11) Afluorescent substance represented by ZnS:Cu; (12) A fluorescentsubstance represented by (Zn,Cd) S:Cu, Mn; (13) A fluorescent substancerepresented by Re₂O₂S:Eu in which Re represents at least one elementselected from Sc, Y, La, Gd and Lu.
 32. The light emitting device as inone of claims 23-30: wherein said first fluorescent has at least afluorescent substance represented by (M_(1-a-b)Eu_(a)L1_(b))₁₀(PO₄)₆Q₂in which M1 represents at least one kind of element selected from Mg,Ca, Ba, Sr and Zn, L1 represents at least one kind of element selectedfrom Mn, Fe, Cr and Sn, and Q represents at least one kind of halogenelement selected from F, Cl, Br and I, where 0.0001≦a≦0.5 and0.0001≦b≦0.5 and one or more fluorescent substance having compositiondifferent from said at least a fluorescent substance.
 33. The lightemitting device according to claims 31 or 32: wherein said firstfluorescent has at least a fluorescent substance represented by(M_(1-a-b)Eu_(a)L1_(b))₁₀(PO₄)₆Q₂ in which M1 represents at least onekind of element selected from Mg, Ca, Ba, Sr and Zn, L1 represents atleast one kind of element selected from Mn, Fe, Cr and Sn, and Qrepresents at least one kind of halogen element selected from F, Cl, Brand I, where 0.0001≦a≦0.5 and 0.0001≦b≦0.5 and one or more fluorescentsubstance having composition different from said at least a fluorescentsubstance, and wherein said second fluorescent substance is afluorescent substance based on cerium-activated yttrium aluminum oxide.34. The light emitting device according to claims 31 or 32: wherein saidfirst fluorescent substance has a fluorescent substance represented by(M_(1-a-b)Eu_(a)L1_(b))₁₀(PO₄)₆Q₂ and a fluorescent substancerepresented by (M_(1-a)Eu_(b))₁₀(PO₄)₆Q₂, in which M1 represents atleast one kind of element selected from Mg, Ca, Ba, Sr and Zn, L1represents at least one kind of element selected from Mn, Fe, Cr and Sn,and Q represents at least one kind of halogen element selected from F,Cl, Br and I, where 0.0001≦a≦0.5 and 0.0001≦b≦0.5}, and wherein saidsecond fluorescent substance is a fluorescent substance based oncerium-activated yttrium aluminum oxide.
 35. The light emitting deviceaccording to claims 31 or 32: wherein said first fluorescent substancehas a fluorescent substance represented by(M_(1-a-b)Eu_(a)L1_(b))₁₀(PO₄)₆Q₂, a fluorescent substance representedby (M_(1-a)Eu_(a))₁₀(PO₄)₆Q₂ and a fluorescent substance represented by(M_(1-a)Eu_(a))₄Al₁₄O₂₅, in which M1 represents at least one kind ofelement selected from Mg, Ca, Ba, Sr and Zn, L1 represents at least onekind of element selected from Mn, Fe, Cr and Sn, and Q represents atleast one kind of halogen element selected from F, Cl, Br and I, where0.0001≦a≦0.5 and 0.0001≦b≦0.5, and wherein said second fluorescentsubstance is a fluorescent substance based on cerium-activated yttriumaluminum oxide.
 36. The light emitting device according to claims 31 or32: wherein said first fluorescent substance has a fluorescent substancerepresented by (M_(1-a-b)Eu_(a)L1_(b))₁₀(PO₄)₆Q₂, a fluorescentsubstance represented by (M_(1-a)Eu_(a))₁₀(PO₄)₆Q₂, a fluorescentsubstance represented by (M_(1-a)Eu_(a))₄Al₁₄O₂₅ and a fluorescentsubstance represented by Re₂O₂S:Eu in which M1 represents at least onekind of element selected from Mg, Ca, Ba, Sr and Zn, L1 represents atleast one kind of element selected from Mn, Fe, Cr and Sn, Q representsat least one kind of halogen element selected from F, Cl, Br and I, andRe represents at least one element selected from Sc, Y, La, Gd and Lu,where 0.0001≦a≦0.5 and 0.0001≦b≦0.5, and wherein said second fluorescentsubstance is a fluorescent substance based on cerium-activated yttriumaluminum oxide.
 37. The light emitting device as in one of claims 23-36:wherein the light emitting layer of said light emitting element is madeof a nitride semiconductor that includes at least In and Ga.
 38. Thelight emitting device as in one of claims 23-36: wherein the lightemitting layer of said light emitting element is made of a nitridesemiconductor that includes at least Ga and Al.